chore: cleanup unused code and dead imports

lib/models/track.dart

@@ -2,7 +2,6 @@ import 'package:json_annotation/json_annotation.dart';
 
 part 'track.g.dart';
 
-/// Track model representing a music track
 @JsonSerializable()
 class Track {
   final String id;
@@ -18,9 +17,9 @@ class Track {
   final String? releaseDate;
   final String? deezerId;
   final ServiceAvailability? availability;
-  final String? source; // Extension ID that provided this track (null for built-in sources)
-  final String? albumType; // album, single, ep, compilation (from metadata API)
-  final String? itemType; // track, album, playlist - for extension search results
+  final String? source;
+  final String? albumType;
+  final String? itemType;
 
   const Track({
     required this.id,
@@ -41,25 +40,19 @@ class Track {
     this.itemType,
   });
 
-  /// Check if this track is a single (based on album_type metadata)
   bool get isSingle => albumType == 'single' || albumType == 'ep';
   
-  /// Check if this is an album item (not a track)
   bool get isAlbumItem => itemType == 'album';
   
-  /// Check if this is a playlist item (not a track)
   bool get isPlaylistItem => itemType == 'playlist';
   
-  /// Check if this is an artist item (not a track)
   bool get isArtistItem => itemType == 'artist';
   
-  /// Check if this is a collection (album, playlist, or artist)
   bool get isCollection => isAlbumItem || isPlaylistItem || isArtistItem;
 
   factory Track.fromJson(Map<String, dynamic> json) => _$TrackFromJson(json);
   Map<String, dynamic> toJson() => _$TrackToJson(this);
   
-  /// Check if this track is from an extension
   bool get isFromExtension => source != null && source!.isNotEmpty;
 }