refactor: extract YouTube download to ytmusic extension and fix UI issues

Remove built-in YouTube/Cobalt download pipeline from Go backend and
Dart frontend. YouTube downloading now requires the ytmusic-spotiflac
extension (with download_provider capability).

Go backend:
- Delete youtube.go (745 lines) and youtube_quality_test.go
- Remove DownloadFromYouTube, IsYouTubeURLExport,
  ExtractYouTubeVideoIDExport from exports.go
- Remove YouTube routing from DownloadTrack and DownloadByStrategy

Dart frontend:
- Remove YouTube from built-in services, bitrate settings, quality UI
- Remove youtubeOpusBitrate/youtubeMp3Bitrate from settings model
- Add migration 7: default service youtube -> tidal
- Remove YouTube l10n keys from all 14 arb files and regenerate
- Update _determineOutputExt to handle opus_/mp3_ quality strings
- Add SAF opus/mp3 metadata embedding in unified branch
- Fix TweenSequence assertion crash (t outside 0.0-1.0)
- Fix store URL TextField styling consistency

Extension changes (gitignored, in extension/YT-Music-SpotiFLAC/):
- Add download_provider type, qualityOptions, network permissions
- Implement checkAvailability and download via SpotubeDL/Cobalt

lib/l10n/app_localizations.dart

@@ -2722,24 +2722,6 @@ abstract class AppLocalizations {
   /// **'Actual quality depends on track availability from the service'**
   String get qualityNote;
 
-  /// Note for YouTube service explaining lossy-only quality
-  ///
-  /// In en, this message translates to:
-  /// **'YouTube provides lossy audio only. Not part of lossless fallback.'**
-  String get youtubeQualityNote;
-
-  /// Title for YouTube Opus bitrate setting
-  ///
-  /// In en, this message translates to:
-  /// **'YouTube Opus Bitrate'**
-  String get youtubeOpusBitrateTitle;
-
-  /// Title for YouTube MP3 bitrate setting
-  ///
-  /// In en, this message translates to:
-  /// **'YouTube MP3 Bitrate'**
-  String get youtubeMp3BitrateTitle;
-
   /// Setting - show quality picker
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -1479,16 +1479,6 @@ class AppLocalizationsDe extends AppLocalizations {
   String get qualityNote =>
       'Die eigentliche Qualität hängt von der Verfügbarkeit des Dienstes ab';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube bietet nur verlustbehaftete Audioqualität. Deswegen ist es kein Teil des verlustfreien Fallbacks.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Qualität vor Download fragen';
 

lib/l10n/app_localizations_en.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsEn extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_es.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsEs extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 
@@ -4466,16 +4456,6 @@ class AppLocalizationsEsEs extends AppLocalizationsEs {
   String get qualityNote =>
       'La calidad real depende de la disponibilidad de la pista del servicio';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Preguntar antes de descargar';
 

lib/l10n/app_localizations_fr.dart

@@ -1457,16 +1457,6 @@ class AppLocalizationsFr extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_hi.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsHi extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_id.dart

@@ -1463,16 +1463,6 @@ class AppLocalizationsId extends AppLocalizations {
   String get qualityNote =>
       'Kualitas sebenarnya tergantung ketersediaan lagu dari layanan';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube hanya menyediakan audio terkompresi (lossy). Bukan bagian dari fallback lossless.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'Bitrate YouTube Opus';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'Kecepatan Bit MP3 YouTube';
-
   @override
   String get downloadAskBeforeDownload => 'Tanya Sebelum Unduh';
 

lib/l10n/app_localizations_ja.dart

@@ -1444,16 +1444,6 @@ class AppLocalizationsJa extends AppLocalizations {
   @override
   String get qualityNote => '実際の品質はサービスからのトラックの可用性に依存します';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus のビットレート';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 のビットレート';
-
   @override
   String get downloadAskBeforeDownload => 'ダウンロード前に確認する';
 

lib/l10n/app_localizations_ko.dart

@@ -1435,16 +1435,6 @@ class AppLocalizationsKo extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_nl.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsNl extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_pt.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsPt extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 
@@ -4463,16 +4453,6 @@ class AppLocalizationsPtPt extends AppLocalizationsPt {
   String get qualityNote =>
       'A qualidade real depende da faixa que estiver disponível no serviço';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Perguntar qualidade antes de baixar';
 

lib/l10n/app_localizations_ru.dart

@@ -1480,16 +1480,6 @@ class AppLocalizationsRu extends AppLocalizations {
   String get qualityNote =>
       'Фактическое качество зависит от доступности треков в сервисе';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube обеспечивает только звук с потерями(Lossy).';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'Битрейт YouTube Opus';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'Битрейт YouTube MP3';
-
   @override
   String get downloadAskBeforeDownload => 'Спрашивать перед скачиванием';
 

lib/l10n/app_localizations_tr.dart

@@ -1461,16 +1461,6 @@ class AppLocalizationsTr extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_zh.dart

@@ -1455,16 +1455,6 @@ class AppLocalizationsZh extends AppLocalizations {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 
@@ -4429,16 +4419,6 @@ class AppLocalizationsZhCn extends AppLocalizationsZh {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 
@@ -6835,16 +6815,6 @@ class AppLocalizationsZhTw extends AppLocalizationsZh {
   String get qualityNote =>
       'Actual quality depends on track availability from the service';
 
-  @override
-  String get youtubeQualityNote =>
-      'YouTube provides lossy audio only. Not part of lossless fallback.';
-
-  @override
-  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
-
-  @override
-  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
-
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/arb/app_de.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube bietet nur verlustbehaftete Audioqualität. Deswegen ist es kein Teil des verlustfreien Fallbacks.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Qualität vor Download fragen",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_en.arb

@@ -1909,18 +1909,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_es_ES.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Preguntar antes de descargar",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_fr.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_hi.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_id.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube hanya menyediakan audio terkompresi (lossy). Bukan bagian dari fallback lossless.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "Bitrate YouTube Opus",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "Kecepatan Bit MP3 YouTube",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Tanya Sebelum Unduh",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_ja.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus のビットレート",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 のビットレート",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "ダウンロード前に確認する",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_ko.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_nl.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_pt_PT.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Perguntar qualidade antes de baixar",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_ru.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube обеспечивает только звук с потерями(Lossy).",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "Битрейт YouTube Opus",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "Битрейт YouTube MP3",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Спрашивать перед скачиванием",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_tr.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_zh_CN.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"

lib/l10n/arb/app_zh_TW.arb

@@ -1773,18 +1773,6 @@
   "@qualityNote": {
     "description": "Note about quality availability"
   },
-  "youtubeQualityNote": "YouTube provides lossy audio only. Not part of lossless fallback.",
-  "@youtubeQualityNote": {
-    "description": "Note for YouTube service explaining lossy-only quality"
-  },
-  "youtubeOpusBitrateTitle": "YouTube Opus Bitrate",
-  "@youtubeOpusBitrateTitle": {
-    "description": "Title for YouTube Opus bitrate setting"
-  },
-  "youtubeMp3BitrateTitle": "YouTube MP3 Bitrate",
-  "@youtubeMp3BitrateTitle": {
-    "description": "Title for YouTube MP3 bitrate setting"
-  },
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {
     "description": "Setting - show quality picker"