feat(app): 完善播放协议搜索与空状态

lib/pages/player/widgets/player_more_sheet.dart

@@ -22,19 +22,25 @@ const double _segmentTrackRadius = 10;
 const double _segmentTrackPadding = 4;
 const double _segmentPadding = 10;
 const List<double> _speedOptions = [0.75, 1.0, 1.25, 1.5, 2.0, 3.0];
-const List<String> _qualityOptions = ['AUTO', '720P', '1080P'];
-const String _autoQuality = 'AUTO';
+const List<String> _qualityOptions = ['AUTO', '360P', '480P', '720P', '1080P'];
 
 /// 更多面板运行状态。
 class PlayerMoreState {
   /// 创建更多面板状态。
-  const PlayerMoreState({required this.speed, required this.qualities});
+  const PlayerMoreState({
+    required this.speed,
+    required this.qualities,
+    this.selectedQuality = 'AUTO',
+  });
 
   /// 当前倍速。
   final double speed;
 
   /// 后端下发的清晰度档位。
   final List<String> qualities;
+
+  /// 当前选中的档位，如 AUTO / 720P。
+  final String selectedQuality;
 }
 
 /// 更多面板动作集合。
@@ -44,6 +50,7 @@ class PlayerMoreActions {
     required this.onSpeedChanged,
     required this.onClear,
     required this.onDownload,
+    required this.onQualityChanged,
     this.onPip,
   });
 
@@ -56,6 +63,9 @@ class PlayerMoreActions {
   /// 离线缓存当前集。
   final VoidCallback onDownload;
 
+  /// 切换清晰度。成功返回 true；失败时面板恢复到上一档。
+  final Future<bool> Function(String quality) onQualityChanged;
+
   /// 进入小窗播放；平台不支持时为 null。
   final VoidCallback? onPip;
 }
@@ -85,6 +95,7 @@ class PlayerMoreSheet extends StatefulWidget {
 
 class _PlayerMoreSheetState extends State<PlayerMoreSheet> {
   late double _speed = widget.state.speed;
+  late String _quality = widget.state.selectedQuality.toUpperCase();
 
   @override
   Widget build(BuildContext context) {
@@ -247,19 +258,31 @@ class _PlayerMoreSheetState extends State<PlayerMoreSheet> {
     );
   }
 
+  Future<void> _chooseQuality(String quality) async {
+    if (_quality == quality) return;
+    final previous = _quality;
+    setState(() => _quality = quality);
+    final switched = await widget.actions.onQualityChanged(quality);
+    if (!mounted || switched) return;
+    setState(() => _quality = previous);
+  }
+
+  bool _hasQuality(String quality) {
+    final wanted = quality.toUpperCase();
+    for (final item in widget.state.qualities) {
+      if (item.toUpperCase() == wanted) return true;
+    }
+    return false;
+  }
+
   Widget _qualitySegment(AppLocalizations l10n, String quality) {
-    final enabled = widget.state.qualities.contains(quality);
-    final selected =
-        quality == _autoQuality && enabled ||
-        !widget.state.qualities.contains(_autoQuality) &&
-            widget.state.qualities.isNotEmpty &&
-            widget.state.qualities.first == quality;
+    final enabled = _hasQuality(quality);
     return _SegmentButton(
       key: Key('player-more-quality-$quality'),
       label: enabled ? quality : '$quality · ${l10n.qualityUnavailable}',
-      selected: selected,
+      selected: enabled && _quality == quality,
       enabled: enabled,
-      onTap: enabled ? () {} : null,
+      onTap: enabled ? () => _chooseQuality(quality) : null,
     );
   }