v3.7.0: roll back from v4, remove internal player — v3 is already complete

Version rolled back from v4.x to v3.7.0. After extensive work on v4's
internal streaming engine, smart queue, DASH pipeline, and media controls,
we realized v3 was already feature-complete. Adding more big features
only made maintenance increasingly difficult and the developer's life
miserable. Stripped back to what works: external player only, cleaner
codebase, sustainable long-term.

- Remove just_audio, audio_service, audio_session and entire internal
  playback engine (smart queue, notification, shuffle/repeat, prefetch)
- Remove PlaybackItem model, MiniPlayerBar widget, notification drawables
- Remove playerMode setting (external-only now)
- Migrate MainActivity from AudioServiceFragmentActivity to
  FlutterFragmentActivity
- Migrate Qobuz to MusicDL API
- Update changelog with v3.7.0 rollback explanation

lib/widgets/track_collection_quick_actions.dart

@@ -1,18 +1,10 @@
-import 'dart:async';
-
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:spotiflac_android/l10n/l10n.dart';
 import 'package:spotiflac_android/models/track.dart';
-import 'package:spotiflac_android/providers/download_queue_provider.dart';
 import 'package:spotiflac_android/providers/library_collections_provider.dart';
-import 'package:spotiflac_android/providers/local_library_provider.dart';
-import 'package:spotiflac_android/providers/playback_provider.dart';
-import 'package:spotiflac_android/providers/settings_provider.dart';
 import 'package:spotiflac_android/services/cover_cache_manager.dart';
-import 'package:spotiflac_android/utils/file_access.dart';
-import 'package:spotiflac_android/widgets/download_service_picker.dart';
 import 'package:spotiflac_android/widgets/playlist_picker_sheet.dart';
 import 'package:spotiflac_android/utils/clickable_metadata.dart';
 
@@ -64,9 +56,6 @@ class _TrackOptionsSheet extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final colorScheme = Theme.of(context).colorScheme;
-    final settings = ref.watch(settingsProvider);
-    final rootContext = Navigator.of(context, rootNavigator: true).context;
-    final container = ProviderScope.containerOf(rootContext, listen: false);
 
     final isLoved = ref.watch(
       libraryCollectionsProvider.select((state) => state.isLoved(track)),
@@ -174,46 +163,6 @@ class _TrackOptionsSheet extends ConsumerWidget {
               ),
 
               // Action items (matches _QualityOption style)
-              _OptionTile(
-                icon: Icons.download_rounded,
-                title: 'Download & Play',
-                onTap: () async {
-                  Navigator.pop(context);
-                  final playedLocal = await _playLocalIfAvailable(
-                    container,
-                    rootContext,
-                  );
-                  if (playedLocal) {
-                    return;
-                  }
-                  if (!rootContext.mounted) {
-                    return;
-                  }
-
-                  if (settings.askQualityBeforeDownload) {
-                    DownloadServicePicker.show(
-                      rootContext,
-                      trackName: track.name,
-                      artistName: track.artistName,
-                      coverUrl: track.coverUrl,
-                      onSelect: (quality, service) {
-                        _enqueueDownloadAndAutoPlay(
-                          container: container,
-                          context: rootContext,
-                          service: service,
-                          quality: quality,
-                        );
-                      },
-                    );
-                  } else {
-                    _enqueueDownloadAndAutoPlay(
-                      container: container,
-                      context: rootContext,
-                      service: settings.defaultService,
-                    );
-                  }
-                },
-              ),
               _OptionTile(
                 icon: isLoved ? Icons.favorite : Icons.favorite_border,
                 iconColor: isLoved ? colorScheme.error : null,
@@ -282,138 +231,6 @@ class _TrackOptionsSheet extends ConsumerWidget {
       ),
     );
   }
-
-  Future<bool> _playLocalIfAvailable(
-    ProviderContainer container,
-    BuildContext context,
-  ) async {
-    final localState = container.read(localLibraryProvider);
-    final historyState = container.read(downloadHistoryProvider);
-    final historyNotifier = container.read(downloadHistoryProvider.notifier);
-
-    try {
-      DownloadHistoryItem? historyItem = historyNotifier.getBySpotifyId(
-        track.id,
-      );
-      final isrc = track.isrc?.trim();
-      historyItem ??= (isrc != null && isrc.isNotEmpty)
-          ? historyNotifier.getByIsrc(isrc)
-          : null;
-      historyItem ??= historyState.findByTrackAndArtist(
-        track.name,
-        track.artistName,
-      );
-
-      if (historyItem != null) {
-        final exists = await fileExists(historyItem.filePath);
-        if (exists) {
-          await container
-              .read(playbackProvider.notifier)
-              .playLocalPath(
-                path: historyItem.filePath,
-                title: track.name,
-                artist: track.artistName,
-                album: track.albumName,
-                coverUrl: track.coverUrl ?? '',
-              );
-          return true;
-        }
-        historyNotifier.removeFromHistory(historyItem.id);
-      }
-
-      var localItem = (isrc != null && isrc.isNotEmpty)
-          ? localState.getByIsrc(isrc)
-          : null;
-      localItem ??= localState.findByTrackAndArtist(
-        track.name,
-        track.artistName,
-      );
-
-      if (localItem != null && await fileExists(localItem.filePath)) {
-        await container
-            .read(playbackProvider.notifier)
-            .playLocalPath(
-              path: localItem.filePath,
-              title: localItem.trackName,
-              artist: localItem.artistName,
-              album: localItem.albumName,
-              coverUrl: localItem.coverPath ?? track.coverUrl ?? '',
-            );
-        return true;
-      }
-    } catch (e) {
-      if (context.mounted) {
-        ScaffoldMessenger.of(context).showSnackBar(
-          SnackBar(content: Text(context.l10n.snackbarCannotOpenFile('$e'))),
-        );
-      }
-      return true;
-    }
-
-    return false;
-  }
-
-  void _enqueueDownloadAndAutoPlay({
-    required ProviderContainer container,
-    required BuildContext context,
-    required String service,
-    String? quality,
-  }) {
-    container
-        .read(downloadQueueProvider.notifier)
-        .addToQueue(track, service, qualityOverride: quality);
-    if (context.mounted) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(context.l10n.snackbarAddedToQueue(track.name))),
-      );
-    }
-    unawaited(_waitForDownloadedFileAndPlay(container, context));
-  }
-
-  Future<void> _waitForDownloadedFileAndPlay(
-    ProviderContainer container,
-    BuildContext context,
-  ) async {
-    const maxAttempts = 180; // up to ~3 minutes
-    for (var i = 0; i < maxAttempts; i++) {
-      final item = _findHistoryMatch(container);
-      if (item != null && await fileExists(item.filePath)) {
-        try {
-          await container
-              .read(playbackProvider.notifier)
-              .playLocalPath(
-                path: item.filePath,
-                title: track.name,
-                artist: track.artistName,
-                album: track.albumName,
-                coverUrl: track.coverUrl ?? '',
-              );
-        } catch (e) {
-          if (context.mounted) {
-            ScaffoldMessenger.of(context).showSnackBar(
-              SnackBar(
-                content: Text(context.l10n.snackbarCannotOpenFile('$e')),
-              ),
-            );
-          }
-        }
-        return;
-      }
-      await Future.delayed(const Duration(seconds: 1));
-    }
-  }
-
-  DownloadHistoryItem? _findHistoryMatch(ProviderContainer container) {
-    final historyState = container.read(downloadHistoryProvider);
-    final historyNotifier = container.read(downloadHistoryProvider.notifier);
-    final isrc = track.isrc?.trim();
-
-    return historyNotifier.getBySpotifyId(track.id) ??
-        ((isrc != null && isrc.isNotEmpty)
-            ? historyNotifier.getByIsrc(isrc)
-            : null) ??
-        historyState.findByTrackAndArtist(track.name, track.artistName);
-  }
 }
 
 /// Styled like _QualityOption in download_service_picker.dart