fix(player): 优化封面过渡与换集起播

lib/core/data/services/playback_session.dart

@@ -41,7 +41,6 @@ class PlaybackSession extends ChangeNotifier {
   final Future<void> Function()? waitForFrame;
   final PlaybackCoordinator _coordinator;
   final Set<_PlayerSlot> _live = {};
-  final Set<String> _pausedEpisodeIds = {};
   _PlayerSlot? _active;
   _PlayerSlot? _next;
   _PlayerSlot? _previous;
@@ -207,9 +206,9 @@ class PlaybackSession extends ChangeNotifier {
     int? previousIndex,
   }) async {
     if (_closed || index < 0 || index >= episodes.length) return;
-    // 新集默认起播；用户手动暂停过的同一集滑回时继续尊重暂停。
+    // 切换到不同剧集时恢复播放；仍停留在同一集时保留用户暂停。
     if (!_selected || index != _currentIndex) {
-      _userWantsPlay = !_pausedEpisodeIds.contains(episodes[index].id);
+      _userWantsPlay = true;
     }
     final request = ++_generation;
     _selected = true;

lib/core/data/services/playback_session_controls.dart

@@ -37,16 +37,8 @@ extension PlaybackSessionControls on PlaybackSession {
     _syncPlayback();
   }
 
-  /// 记录用户播放意图；手动暂停的剧集滑回时不再自动起播。
+  /// 记录用户播放意图；切换剧集时会在 [PlaybackSession.select] 中恢复播放。
   void setUserWantsPlay(bool value) {
-    if (episodes.isNotEmpty) {
-      final episodeId = episodes[_currentIndex].id;
-      if (value) {
-        _pausedEpisodeIds.remove(episodeId);
-      } else {
-        _pausedEpisodeIds.add(episodeId);
-      }
-    }
     _userWantsPlay = value;
     _syncPlayback();
     _notify();