feat: multi-select batch delete and album grouping in history

- Add multi-select mode with long-press to select tracks
- Add bottom action bar for selection (Material 3 style)
- Add filter tabs: All/Albums/Singles
- Add album grouping view when Albums filter selected
- Add DownloadedAlbumScreen for viewing tracks in an album
- Reactive UI updates when tracks deleted
- Auto-pop when album has <2 tracks
- Update issue templates with (Stable Version) text
- Bump version to 2.2.8

lib/providers/settings_provider.dart

@@ -148,6 +148,11 @@ class SettingsNotifier extends Notifier<AppSettings> {
     _saveSettings();
   }
 
+  void setHistoryFilterMode(String mode) {
+    state = state.copyWith(historyFilterMode: mode);
+    _saveSettings();
+  }
+
   void setAskQualityBeforeDownload(bool enabled) {
     state = state.copyWith(askQualityBeforeDownload: enabled);
     _saveSettings();