feat: responsive layout tuning, cache management page, and improved recent access UX

- Add responsive scaling across album, artist, playlist, downloaded album, local album, queue, setup, and tutorial screens to prevent overflow on smaller devices
- Add new Storage & Cache management page (Settings > Storage & Cache) with per-category clear and cleanup actions
- Extract normalizedHeaderTopPadding utility for consistent app bar padding
- Improve home search Recent Access behavior: show when focused with empty input, hide stale results during active recent mode
- Add excluded-downloaded-count tracking to local library scan stats
- Add recentEmpty and recentShowAllDownloads l10n keys (EN + ID)
- Add full cache management l10n keys (EN + ID)
- Fix about_page indentation and formatting consistency
- Fix appearance_settings_page formatting
- Fix downloaded_album_screen and local_album_screen formatting and responsive sizing

lib/models/settings.dart

@@ -19,6 +19,7 @@ class AppSettings {
   final String updateChannel;
   final bool hasSearchedBefore;
   final String folderOrganization;
+  final bool useAlbumArtistForFolders;
   final String historyViewMode;
   final String historyFilterMode;
   final bool askQualityBeforeDownload;
@@ -63,6 +64,7 @@ class AppSettings {
     this.updateChannel = 'stable',
     this.hasSearchedBefore = false,
     this.folderOrganization = 'none',
+    this.useAlbumArtistForFolders = true,
     this.historyViewMode = 'grid',
     this.historyFilterMode = 'all',
     this.askQualityBeforeDownload = true,
@@ -106,6 +108,7 @@ class AppSettings {
     String? updateChannel,
     bool? hasSearchedBefore,
     String? folderOrganization,
+    bool? useAlbumArtistForFolders,
     String? historyViewMode,
     String? historyFilterMode,
     bool? askQualityBeforeDownload,
@@ -149,6 +152,8 @@ class AppSettings {
       updateChannel: updateChannel ?? this.updateChannel,
       hasSearchedBefore: hasSearchedBefore ?? this.hasSearchedBefore,
       folderOrganization: folderOrganization ?? this.folderOrganization,
+      useAlbumArtistForFolders:
+          useAlbumArtistForFolders ?? this.useAlbumArtistForFolders,
       historyViewMode: historyViewMode ?? this.historyViewMode,
       historyFilterMode: historyFilterMode ?? this.historyFilterMode,
       askQualityBeforeDownload: askQualityBeforeDownload ?? this.askQualityBeforeDownload,

lib/models/settings.g.dart

@@ -22,6 +22,7 @@ AppSettings _$AppSettingsFromJson(Map<String, dynamic> json) => AppSettings(
   updateChannel: json['updateChannel'] as String? ?? 'stable',
   hasSearchedBefore: json['hasSearchedBefore'] as bool? ?? false,
   folderOrganization: json['folderOrganization'] as String? ?? 'none',
+  useAlbumArtistForFolders: json['useAlbumArtistForFolders'] as bool? ?? true,
   historyViewMode: json['historyViewMode'] as String? ?? 'grid',
   historyFilterMode: json['historyFilterMode'] as String? ?? 'all',
   askQualityBeforeDownload: json['askQualityBeforeDownload'] as bool? ?? true,
@@ -68,6 +69,7 @@ Map<String, dynamic> _$AppSettingsToJson(AppSettings instance) =>
       'updateChannel': instance.updateChannel,
       'hasSearchedBefore': instance.hasSearchedBefore,
       'folderOrganization': instance.folderOrganization,
+      'useAlbumArtistForFolders': instance.useAlbumArtistForFolders,
       'historyViewMode': instance.historyViewMode,
       'historyFilterMode': instance.historyFilterMode,
       'askQualityBeforeDownload': instance.askQualityBeforeDownload,