refactor(metadata): move cover resolution to extensions

lib/models/settings.dart

@@ -25,7 +25,6 @@ class AppSettings {
   final bool embedReplayGain;
   // Apply ReplayGain/R128 tags as volume normalization in the built-in player.
   final bool playbackNormalization;
-  final bool maxQualityCover;
   final bool isFirstLaunch;
   final bool checkForUpdates;
   final String updateChannel;
@@ -134,7 +133,6 @@ class AppSettings {
     this.embedLyrics = true,
     this.embedReplayGain = false,
     this.playbackNormalization = false,
-    this.maxQualityCover = true,
     this.isFirstLaunch = true,
     this.checkForUpdates = true,
     this.updateChannel = 'stable',
@@ -209,7 +207,6 @@ class AppSettings {
     bool? embedLyrics,
     bool? embedReplayGain,
     bool? playbackNormalization,
-    bool? maxQualityCover,
     bool? isFirstLaunch,
     bool? checkForUpdates,
     String? updateChannel,
@@ -288,7 +285,6 @@ class AppSettings {
       embedReplayGain: embedReplayGain ?? this.embedReplayGain,
       playbackNormalization:
           playbackNormalization ?? this.playbackNormalization,
-      maxQualityCover: maxQualityCover ?? this.maxQualityCover,
       isFirstLaunch: isFirstLaunch ?? this.isFirstLaunch,
       checkForUpdates: checkForUpdates ?? this.checkForUpdates,
       updateChannel: updateChannel ?? this.updateChannel,

lib/models/settings.g.dart

@@ -20,7 +20,6 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   embedLyrics: json['embedLyrics'] as bool? ?? true,
   embedReplayGain: json['embedReplayGain'] as bool? ?? false,
   playbackNormalization: json['playbackNormalization'] as bool? ?? false,
-  maxQualityCover: json['maxQualityCover'] as bool? ?? true,
   isFirstLaunch: json['isFirstLaunch'] as bool? ?? true,
   checkForUpdates: json['checkForUpdates'] as bool? ?? true,
   updateChannel: json['updateChannel'] as String? ?? 'stable',
@@ -116,7 +115,6 @@ Map<String, dynamic> _$AppSettingsToJson(
   'embedLyrics': instance.embedLyrics,
   'embedReplayGain': instance.embedReplayGain,
   'playbackNormalization': instance.playbackNormalization,
-  'maxQualityCover': instance.maxQualityCover,
   'isFirstLaunch': instance.isFirstLaunch,
   'checkForUpdates': instance.checkForUpdates,
   'updateChannel': instance.updateChannel,