feat(lyrics): keep the screen awake while viewing lyrics

lib/models/settings.dart

@@ -81,6 +81,7 @@ class AppSettings {
   extensionVerificationBrowserMode; // 'external_first' or 'in_app_first'
   final String locale;
   final String lyricsMode;
+  final bool keepScreenOnLyrics;
   final bool autoConvertDownloads;
   // Re-download a Hi-Res request at LOSSLESS when the file measures as fake.
   final bool redownloadFakeHiRes;
@@ -185,6 +186,7 @@ class AppSettings {
     this.extensionVerificationBrowserMode = 'in_app_first',
     this.locale = 'system',
     this.lyricsMode = 'embed',
+    this.keepScreenOnLyrics = true,
     this.autoConvertDownloads = false,
     this.redownloadFakeHiRes = false,
     this.autoConvertFormat = 'mp3',
@@ -281,6 +283,7 @@ class AppSettings {
     String? extensionVerificationBrowserMode,
     String? locale,
     String? lyricsMode,
+    bool? keepScreenOnLyrics,
     bool? autoConvertDownloads,
     bool? redownloadFakeHiRes,
     String? autoConvertFormat,
@@ -382,6 +385,7 @@ class AppSettings {
           this.extensionVerificationBrowserMode,
       locale: locale ?? this.locale,
       lyricsMode: lyricsMode ?? this.lyricsMode,
+      keepScreenOnLyrics: keepScreenOnLyrics ?? this.keepScreenOnLyrics,
       autoConvertDownloads: autoConvertDownloads ?? this.autoConvertDownloads,
       redownloadFakeHiRes: redownloadFakeHiRes ?? this.redownloadFakeHiRes,
       autoConvertFormat: autoConvertFormat ?? this.autoConvertFormat,

lib/models/settings.g.dart

@@ -67,6 +67,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
       json['extensionVerificationBrowserMode'] as String? ?? 'in_app_first',
   locale: json['locale'] as String? ?? 'system',
   lyricsMode: json['lyricsMode'] as String? ?? 'embed',
+  keepScreenOnLyrics: json['keepScreenOnLyrics'] as bool? ?? true,
   autoConvertDownloads: json['autoConvertDownloads'] as bool? ?? false,
   redownloadFakeHiRes: json['redownloadFakeHiRes'] as bool? ?? false,
   autoConvertFormat: json['autoConvertFormat'] as String? ?? 'mp3',
@@ -164,6 +165,7 @@ Map<String, dynamic> _$AppSettingsToJson(
   'extensionVerificationBrowserMode': instance.extensionVerificationBrowserMode,
   'locale': instance.locale,
   'lyricsMode': instance.lyricsMode,
+  'keepScreenOnLyrics': instance.keepScreenOnLyrics,
   'autoConvertDownloads': instance.autoConvertDownloads,
   'redownloadFakeHiRes': instance.redownloadFakeHiRes,
   'autoConvertFormat': instance.autoConvertFormat,