fix(favorite): 收藏状态变化时主页实时刷新

之前主页收藏列表只在启动或从文件列表返回时重查，
在播放页/文件列表点红心，主页不会变。

- 新增 FavoriteEvents（songPath 事件）
- 文件列表、播放页收藏/取消后 publish
- 主页订阅后重新拉取收藏列表

lib/pages/home_page.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import '../services/audio_service.dart';
+import '../services/favorite_events.dart';
 import '../services/metadata_events.dart';
 import '../services/webdav_service.dart';
 import '../widgets/magnetic_scroll_physics.dart';
@@ -166,6 +167,7 @@ class _HomePageState extends BaseState<HomePage> {
   int _homeTab = 0;
   final PageController _homePageController = PageController();
   StreamSubscription<MetadataUpdate>? _metaSub;
+  StreamSubscription<String>? _favSub;
   List<PlaylistSummary> _playlistSummaries = [];
 
   // ========== 滚动控制 ==========
@@ -204,6 +206,7 @@ class _HomePageState extends BaseState<HomePage> {
     super.initState();
     _scrollController = ScrollController()..addListener(_onScroll);
     _metaSub = MetadataEvents().stream.listen(_onMetadataUpdate);
+    _favSub = FavoriteEvents().stream.listen((_) => _onFavoriteChanged());
     _initWebDAV();
 
     WidgetsBinding.instance.addPostFrameCallback((_) {
@@ -214,6 +217,7 @@ class _HomePageState extends BaseState<HomePage> {
   @override
   void dispose() {
     _metaSub?.cancel();
+    _favSub?.cancel();
     _homePageController.dispose();
     _scrollController.dispose();
     super.dispose();
@@ -245,6 +249,12 @@ class _HomePageState extends BaseState<HomePage> {
     }
   }
 
+  /// 任何位置收藏/取消收藏后，重新拉一次收藏列表
+  Future<void> _onFavoriteChanged() async {
+    await _loadFavoritesFromDb();
+    if (mounted) safeSetState(() {});
+  }
+
   /// 元数据补全后，按 path 更新收藏列表里的对应行
   void _onMetadataUpdate(MetadataUpdate update) {
     final index = _favorites.indexWhere((item) => item.path == update.path);

lib/pages/player_page.dart

@@ -5,6 +5,7 @@ import 'package:provider/provider.dart';
 import '../base/base_state.dart';
 import '../database/song_database.dart';
 import '../services/audio_service.dart';
+import '../services/favorite_events.dart';
 
 class PlayerPage extends StatefulWidget {
   final VoidCallback? onClose;
@@ -138,6 +139,7 @@ class _PlayerPageState extends BaseState<PlayerPage> {
   Future<void> _toggleFavorite(Song song) async {
     try {
       await SongDatabase().toggleFavorite(song.id);
+      FavoriteEvents().publish(song.id);
       final favorite = await SongDatabase().isFavorite(song.id);
       if (!mounted) return;
       setState(() => _isFavorite = favorite);

lib/pages/webdav_file_list_page.dart

@@ -7,6 +7,7 @@ import '../base/base_state.dart';
 import '../controllers/playback_controller.dart';
 import '../database/song_database.dart';
 import '../services/audio_service.dart';
+import '../services/favorite_events.dart';
 import '../services/metadata_events.dart';
 import '../widgets/song_artwork.dart';
 import '../widgets/add_to_playlist_sheet.dart';
@@ -92,6 +93,7 @@ class _WebDAVFileListPageState extends BaseState<WebDAVFileListPage> {
     final wasFavorite = _favoritePaths.contains(path);
     try {
       await SongDatabase().toggleFavorite(path);
+      FavoriteEvents().publish(path);
       if (!mounted) return;
       safeSetState(() {
         final next = {..._favoritePaths};

lib/services/favorite_events.dart

@@ -0,0 +1,22 @@
+// lib/services/favorite_events.dart
+import 'dart:async';
+
+/// 收藏状态变化事件。
+///
+/// 文件列表、播放页都能收藏/取消收藏，主页的收藏列表需要跟着变，
+/// 否则要退出重进才看得到。
+class FavoriteEvents {
+  static final FavoriteEvents _instance = FavoriteEvents._internal();
+  factory FavoriteEvents() => _instance;
+  FavoriteEvents._internal();
+
+  final StreamController<String> _controller =
+      StreamController<String>.broadcast();
+
+  Stream<String> get stream => _controller.stream;
+
+  void publish(String songPath) {
+    if (songPath.isEmpty) return;
+    _controller.add(songPath);
+  }
+}