feat: YouTube customizable bitrate, improved title matching, SpotubeDL engine fallback

- Add configurable YouTube Opus (96-256kbps) and MP3 (96-320kbps) bitrates
- Improve title matching with loose normalization for symbol-heavy tracks
- Add SpotubeDL engine v2 fallback for MP3 requests
- Improve filename sanitization in track metadata screen
- Bump version to 3.6.9+82

lib/l10n/app_localizations.dart

@@ -3508,6 +3508,42 @@ abstract class AppLocalizations {
   /// **'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;
+
+  /// Subtitle showing current bitrate and valid range
+  ///
+  /// In en, this message translates to:
+  /// **'{bitrate}kbps ({min}-{max})'**
+  String youtubeBitrateSubtitle(int bitrate, int min, int max);
+
+  /// Helper text for manual YouTube bitrate input
+  ///
+  /// In en, this message translates to:
+  /// **'Enter custom bitrate ({min}-{max} kbps)'**
+  String youtubeBitrateInputHelp(int min, int max);
+
+  /// Label for YouTube bitrate input field
+  ///
+  /// In en, this message translates to:
+  /// **'Bitrate (kbps)'**
+  String get youtubeBitrateFieldLabel;
+
+  /// Validation error for invalid YouTube bitrate input
+  ///
+  /// In en, this message translates to:
+  /// **'Bitrate must be between {min} and {max} kbps'**
+  String youtubeBitrateValidationError(int min, int max);
+
   /// Setting - show quality picker
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -1944,6 +1944,30 @@ class AppLocalizationsDe extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_en.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsEn extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_es.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsEs extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_fr.dart

@@ -1929,6 +1929,30 @@ class AppLocalizationsFr extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_hi.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsHi extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_id.dart

@@ -1935,6 +1935,30 @@ class AppLocalizationsId extends AppLocalizations {
   String get youtubeQualityNote =>
       'YouTube provides lossy audio only. Not part of lossless fallback.';
 
+  @override
+  String get youtubeOpusBitrateTitle => 'Bitrate Opus YouTube';
+
+  @override
+  String get youtubeMp3BitrateTitle => 'Bitrate MP3 YouTube';
+
+  @override
+  String youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Masukkan bitrate manual ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate harus antara $min dan $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Tanya Sebelum Unduh';
 

lib/l10n/app_localizations_ja.dart

@@ -1911,6 +1911,30 @@ class AppLocalizationsJa extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'ダウンロード前に確認する';
 

lib/l10n/app_localizations_ko.dart

@@ -1922,6 +1922,30 @@ class AppLocalizationsKo extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_nl.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsNl extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_pt.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsPt extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_ru.dart

@@ -1963,6 +1963,30 @@ class AppLocalizationsRu extends AppLocalizations {
   String get youtubeQualityNote =>
       'YouTube обеспечивает только звук с потерями(Lossy).';
 
+  @override
+  String get youtubeOpusBitrateTitle => 'YouTube Opus Bitrate';
+
+  @override
+  String get youtubeMp3BitrateTitle => 'YouTube MP3 Bitrate';
+
+  @override
+  String youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Спрашивать перед скачиванием';
 

lib/l10n/app_localizations_tr.dart

@@ -1938,6 +1938,30 @@ class AppLocalizationsTr extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/app_localizations_zh.dart

@@ -1923,6 +1923,30 @@ class AppLocalizationsZh extends AppLocalizations {
   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 youtubeBitrateSubtitle(int bitrate, int min, int max) {
+    return '${bitrate}kbps ($min-$max)';
+  }
+
+  @override
+  String youtubeBitrateInputHelp(int min, int max) {
+    return 'Enter custom bitrate ($min-$max kbps)';
+  }
+
+  @override
+  String get youtubeBitrateFieldLabel => 'Bitrate (kbps)';
+
+  @override
+  String youtubeBitrateValidationError(int min, int max) {
+    return 'Bitrate must be between $min and $max kbps';
+  }
+
   @override
   String get downloadAskBeforeDownload => 'Ask Before Download';
 

lib/l10n/arb/app_en.arb

@@ -1420,6 +1420,37 @@
   "@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"},
+  "youtubeBitrateSubtitle": "{bitrate}kbps ({min}-{max})",
+  "@youtubeBitrateSubtitle": {
+    "description": "Subtitle showing current bitrate and valid range",
+    "placeholders": {
+      "bitrate": {"type": "int"},
+      "min": {"type": "int"},
+      "max": {"type": "int"}
+    }
+  },
+  "youtubeBitrateInputHelp": "Enter custom bitrate ({min}-{max} kbps)",
+  "@youtubeBitrateInputHelp": {
+    "description": "Helper text for manual YouTube bitrate input",
+    "placeholders": {
+      "min": {"type": "int"},
+      "max": {"type": "int"}
+    }
+  },
+  "youtubeBitrateFieldLabel": "Bitrate (kbps)",
+  "@youtubeBitrateFieldLabel": {"description": "Label for YouTube bitrate input field"},
+  "youtubeBitrateValidationError": "Bitrate must be between {min} and {max} kbps",
+  "@youtubeBitrateValidationError": {
+    "description": "Validation error for invalid YouTube bitrate input",
+    "placeholders": {
+      "min": {"type": "int"},
+      "max": {"type": "int"}
+    }
+  },
 
   "downloadAskBeforeDownload": "Ask Before Download",
   "@downloadAskBeforeDownload": {"description": "Setting - show quality picker"},

lib/l10n/arb/app_id.arb

@@ -2498,18 +2498,69 @@
   "@lossyFormatOpusSubtitle": {
     "description": "Opus format description"
   },
-  "qualityNote": "Kualitas sebenarnya tergantung ketersediaan lagu dari layanan",
-  "@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"
-  },
-  "downloadAskBeforeDownload": "Tanya Sebelum Unduh",
-  "@downloadAskBeforeDownload": {
-    "description": "Setting - show quality picker"
-  },
+  "qualityNote": "Kualitas sebenarnya tergantung ketersediaan lagu dari layanan",
+  "@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": "Bitrate Opus YouTube",
+  "@youtubeOpusBitrateTitle": {
+    "description": "Title for YouTube Opus bitrate setting"
+  },
+  "youtubeMp3BitrateTitle": "Bitrate MP3 YouTube",
+  "@youtubeMp3BitrateTitle": {
+    "description": "Title for YouTube MP3 bitrate setting"
+  },
+  "youtubeBitrateSubtitle": "{bitrate}kbps ({min}-{max})",
+  "@youtubeBitrateSubtitle": {
+    "description": "Subtitle showing current bitrate and valid range",
+    "placeholders": {
+      "bitrate": {
+        "type": "int"
+      },
+      "min": {
+        "type": "int"
+      },
+      "max": {
+        "type": "int"
+      }
+    }
+  },
+  "youtubeBitrateInputHelp": "Masukkan bitrate manual ({min}-{max} kbps)",
+  "@youtubeBitrateInputHelp": {
+    "description": "Helper text for manual YouTube bitrate input",
+    "placeholders": {
+      "min": {
+        "type": "int"
+      },
+      "max": {
+        "type": "int"
+      }
+    }
+  },
+  "youtubeBitrateFieldLabel": "Bitrate (kbps)",
+  "@youtubeBitrateFieldLabel": {
+    "description": "Label for YouTube bitrate input field"
+  },
+  "youtubeBitrateValidationError": "Bitrate harus antara {min} dan {max} kbps",
+  "@youtubeBitrateValidationError": {
+    "description": "Validation error for invalid YouTube bitrate input",
+    "placeholders": {
+      "min": {
+        "type": "int"
+      },
+      "max": {
+        "type": "int"
+      }
+    }
+  },
+  "downloadAskBeforeDownload": "Tanya Sebelum Unduh",
+  "@downloadAskBeforeDownload": {
+    "description": "Setting - show quality picker"
+  },
   "downloadDirectory": "Direktori Unduhan",
   "@downloadDirectory": {
     "description": "Setting - download folder"