feat(tidal): convert M4A to MP3/Opus for HIGH quality, remove LOSSY option

- Add tidalHighFormat setting (mp3_320 or opus_128) for Tidal HIGH quality
- Add convertM4aToLossy() in FFmpegService for M4A to MP3/Opus conversion
- Remove inefficient LOSSY option (FLAC download then convert)
- Update download_queue_provider to handle HIGH quality conversion
- Clean up LOSSY references from download_service_picker and log messages
- Update Go backend: amazon.go, tidal.go, metadata.go improvements
- UI: minor updates to album, playlist, and home screens

lib/models/settings.dart

@@ -31,10 +31,8 @@ class AppSettings {
   final String albumFolderStructure;
   final bool showExtensionStore;
   final String locale;
-  final bool enableLossyOption;
-  final String lossyFormat;
-  final String lossyBitrate; // e.g., 'mp3_320', 'mp3_256', 'mp3_192', 'mp3_128', 'opus_128', 'opus_96', 'opus_64'
   final String lyricsMode;
+  final String tidalHighFormat; // Format for Tidal HIGH quality: 'mp3_320' or 'opus_128'
   final bool useAllFilesAccess; // Android 13+ only: enable MANAGE_EXTERNAL_STORAGE
 
   const AppSettings({
@@ -65,10 +63,8 @@ class AppSettings {
     this.albumFolderStructure = 'artist_album',
     this.showExtensionStore = true,
     this.locale = 'system',
-    this.enableLossyOption = false,
-    this.lossyFormat = 'mp3',
-    this.lossyBitrate = 'mp3_320',
     this.lyricsMode = 'embed',
+    this.tidalHighFormat = 'mp3_320',
     this.useAllFilesAccess = false,
   });
 
@@ -101,10 +97,8 @@ class AppSettings {
     String? albumFolderStructure,
     bool? showExtensionStore,
     String? locale,
-    bool? enableLossyOption,
-    String? lossyFormat,
-    String? lossyBitrate,
     String? lyricsMode,
+    String? tidalHighFormat,
     bool? useAllFilesAccess,
   }) {
     return AppSettings(
@@ -135,10 +129,8 @@ class AppSettings {
       albumFolderStructure: albumFolderStructure ?? this.albumFolderStructure,
       showExtensionStore: showExtensionStore ?? this.showExtensionStore,
       locale: locale ?? this.locale,
-      enableLossyOption: enableLossyOption ?? this.enableLossyOption,
-      lossyFormat: lossyFormat ?? this.lossyFormat,
-      lossyBitrate: lossyBitrate ?? this.lossyBitrate,
       lyricsMode: lyricsMode ?? this.lyricsMode,
+      tidalHighFormat: tidalHighFormat ?? this.tidalHighFormat,
       useAllFilesAccess: useAllFilesAccess ?? this.useAllFilesAccess,
     );
   }

lib/models/settings.g.dart

@@ -36,10 +36,8 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
       json['albumFolderStructure'] as String? ?? 'artist_album',
   showExtensionStore: json['showExtensionStore'] as bool? ?? true,
   locale: json['locale'] as String? ?? 'system',
-  enableLossyOption: json['enableLossyOption'] as bool? ?? false,
-  lossyFormat: json['lossyFormat'] as String? ?? 'mp3',
-  lossyBitrate: json['lossyBitrate'] as String? ?? 'mp3_320',
   lyricsMode: json['lyricsMode'] as String? ?? 'embed',
+  tidalHighFormat: json['tidalHighFormat'] as String? ?? 'mp3_320',
   useAllFilesAccess: json['useAllFilesAccess'] as bool? ?? false,
 );
 
@@ -72,9 +70,7 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'albumFolderStructure': instance.albumFolderStructure,
       'showExtensionStore': instance.showExtensionStore,
       'locale': instance.locale,
-      'enableLossyOption': instance.enableLossyOption,
-      'lossyFormat': instance.lossyFormat,
-      'lossyBitrate': instance.lossyBitrate,
       'lyricsMode': instance.lyricsMode,
+      'tidalHighFormat': instance.tidalHighFormat,
       'useAllFilesAccess': instance.useAllFilesAccess,
     };