fix(player): 解锁状态登录期内共享，重进播放页不再丢解锁

解锁记录原本是播放页实例的私有集合，退出再进入会先闪一次锁定态，还会
被 selectLocked 提前释放播放器。改为进程内共享的 UnlockedEpisodeRegistry，
由全局注入并在登录态变化时清空；播放器三处渲染分支统一走同一判定，
会话锁态只约束当前页，避免相邻预加载页被误判为锁定。

lib/pages/player/player_binding.dart

@@ -5,6 +5,7 @@ import '../../core/data/repositories/playback_repository.dart';
 import '../../core/data/services/android_picture_in_picture.dart';
 import '../../core/data/services/download_controller.dart';
 import '../../core/data/services/playback_position_cache.dart';
+import '../../core/data/services/unlocked_episode_registry.dart';
 import '../../core/data/services/wallet_controller.dart';
 import 'player_logic.dart';
 
@@ -13,6 +14,7 @@ class PlayerBinding {
     required WatchHistoryRepository history,
     required PlaybackRepository playback,
     required PlaybackPositionCache positionCache,
+    UnlockedEpisodeRegistry? unlockedEpisodes,
     WalletController? wallet,
     DownloadController? downloads,
     bool Function()? isSignedIn,
@@ -20,6 +22,7 @@ class PlayerBinding {
     history: history,
     playback: playback,
     positionCache: positionCache,
+    unlockedEpisodes: unlockedEpisodes,
     pictureInPicture: AndroidPictureInPicture(),
     wallet: wallet,
     downloads: downloads,