feat(ui): 文件列表收藏红心 + 首页收藏绑定 favorites 表

交互调整（按讨论）：
- WebDAV 文件列表：整行点击 = 播放（原来的行为），右侧播放按钮改成收藏红心
  已收藏实心红，未收藏空心；点击即写/删 favorites 表
- 首页"我的收藏"改为读 favorites 表 + songs 元数据；
  从文件列表返回时自动刷新
- 收藏项右侧红心改为真正删除（原来只是内存 removeAt）

修复：
- 收藏列表项透明度绑定 _listReveal，首屏为 0 导致条目完全透明
  （收藏成功但看不到）。收藏项改为固定 opacity 1.0。

验证（真机）：
  列表点红心 -> favorites 表 +1 -> 返回首页 -> 收藏区出现该条目

lib/pages/home_page.dart

@@ -5,6 +5,7 @@ import '../services/webdav_service.dart';
 import '../widgets/magnetic_scroll_physics.dart';
 import 'webdav_setup_page.dart';
 import 'settings_page.dart';
+import '../database/song_database.dart';
 import 'webdav_file_list_page.dart';
 import '../constants/ui_constants.dart';
 import '../base/base_state.dart';
@@ -236,7 +237,7 @@ class _HomePageState extends BaseState<HomePage> {
     safeSetState(() => _isLoading = true);
     try {
       await WebDAVService.instance.loadCredentials();
-      _favorites = [];
+      await _loadFavoritesFromDb();
     } catch (e) {
       _favorites = [];
     } finally {
@@ -244,6 +245,34 @@ class _HomePageState extends BaseState<HomePage> {
     }
   }
 
+  /// 收藏列表直接绑定 favorites 表 + songs 元数据
+  Future<void> _loadFavoritesFromDb() async {
+    final db = SongDatabase();
+    final favRows = await db.getFavorites();
+    final paths = favRows
+        .map((row) => row['song_id'] as String?)
+        .whereType<String>()
+        .toList();
+    final meta = await db.getSongsByPaths(paths);
+
+    final items = <SongItem>[];
+    for (final path in paths) {
+      final row = meta[path];
+      final title = (row?['title'] as String?)?.trim() ?? '';
+      final artist = (row?['artist'] as String?)?.trim() ?? '';
+      final hasTitle = title.isNotEmpty;
+      items.add(SongItem(
+        path: path,
+        fileName: path.split('/').last,
+        title: hasTitle ? title : null,
+        artist: artist.isNotEmpty ? artist : null,
+        sourceTag: '收藏',
+        metadataState: hasTitle ? 'success' : 'unknown',
+      ));
+    }
+    _favorites = items;
+  }
+
   void _playSong(SongItem song) async {
     try {
       // 先校验登录，再开始播放。
@@ -416,6 +445,7 @@ class _HomePageState extends BaseState<HomePage> {
                                     builder: (_) => const WebDAVFileListPage(),
                                   ),
                                 );
+                                await _loadFavoritesFromDb();
                                 _resetSnapState();
                                 safeSetState(() {});
                               } else {
@@ -674,12 +704,11 @@ class _HomePageState extends BaseState<HomePage> {
                               delegate: SliverChildBuilderDelegate(
                                 (context, index) {
                                   final song = _favorites[index];
-                                  final itemProgress =
-                                      (_listReveal * 2 - index / 5)
-                                          .clamp(0.0, 1.0);
 
+                                  // 收藏项不做滚动渐显：_listReveal 在首屏为 0，
+                                  // 会让条目完全透明（看起来"收藏了但不显示"）。
                                   return AnimatedOpacity(
-                                    opacity: itemProgress,
+                                    opacity: 1.0,
                                     duration: const Duration(milliseconds: 150),
                                     child: Padding(
                                       padding: const EdgeInsets.symmetric(
@@ -713,13 +742,14 @@ class _HomePageState extends BaseState<HomePage> {
                                         trailing: IconButton(
                                           icon: const Icon(
                                             Icons.favorite,
-                                            color: Color(0xFFB8D4D0),
+                                            color: Color(0xFFE05C5C),
                                             size: 20,
                                           ),
-                                          onPressed: () {
+                                          onPressed: () async {
-                                            safeSetState(() {
+                                            await SongDatabase()
-                                              _favorites.removeAt(index);
+                                                .removeFavorite(song.path);
-                                            });
+                                            await _loadFavoritesFromDb();
+                                            if (mounted) safeSetState(() {});
                                           },
                                         ),
                                         onTap: () => _playSong(song),

lib/pages/webdav_file_list_page.dart

@@ -27,6 +27,9 @@ class _WebDAVFileListPageState extends BaseState<WebDAVFileListPage> {
   Map<String, Map<String, dynamic>> _metaByPath = {};
   String? _lastSyncedSongPath;
 
+  /// 已收藏的歌曲路径
+  Set<String> _favoritePaths = {};
+
   // 安全解码
   String _safeDecode(String input) {
     try {
@@ -69,6 +72,30 @@ class _WebDAVFileListPageState extends BaseState<WebDAVFileListPage> {
     });
   }
 
+  /// 收藏 / 取消收藏：整行点击是播放，右侧红心专门做收藏
+  Future<void> _toggleFavorite(String path) async {
+    final wasFavorite = _favoritePaths.contains(path);
+    try {
+      await SongDatabase().toggleFavorite(path);
+      if (!mounted) return;
+      safeSetState(() {
+        final next = {..._favoritePaths};
+        if (wasFavorite) {
+          next.remove(path);
+        } else {
+          next.add(path);
+        }
+        _favoritePaths = next;
+      });
+    } catch (e) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text('收藏失败: $e')),
+        );
+      }
+    }
+  }
+
   // ============================================================
   // 加载目录
   // ============================================================
@@ -94,10 +121,22 @@ class _WebDAVFileListPageState extends BaseState<WebDAVFileListPage> {
         debugPrint('⚠️ [WebDAVList] 批量读取元数据失败: $e');
       }
 
+      var favorites = <String>{};
+      try {
+        final favRows = await SongDatabase().getFavorites();
+        favorites = favRows
+            .map((row) => row['song_id'] as String?)
+            .whereType<String>()
+            .toSet();
+      } catch (e) {
+        debugPrint('⚠️ [WebDAVList] 读取收藏失败: $e');
+      }
+
       if (mounted) {
         safeSetState(() {
           _items = items;
           _metaByPath = meta;
+          _favoritePaths = favorites;
           _isLoading = false;
         });
         // 如果当前正在播的歌就在这个目录里，补一次同步
@@ -382,8 +421,16 @@ class _WebDAVFileListPageState extends BaseState<WebDAVFileListPage> {
           ),
         ),
         trailing: IconButton(
-          icon: const Icon(Icons.play_arrow, color: Color(0xFFB8D4D0)),
+          tooltip: '收藏',
-          onPressed: () => _playSong(item),
+          icon: Icon(
+            _favoritePaths.contains(item.path)
+                ? Icons.favorite
+                : Icons.favorite_border,
+            color: _favoritePaths.contains(item.path)
+                ? const Color(0xFFE05C5C)
+                : Colors.grey,
+          ),
+          onPressed: () => _toggleFavorite(item.path),
         ),
         onTap: () => _playSong(item),
       );