feat(player): 进度条拖动预览改用雪碧图

lib/pages/player/player_logic.dart

@@ -149,6 +149,7 @@ class PlayerLogic extends ChangeNotifier {
   Episode displayEpisode(Drama drama, Episode fallback) {
     final number = pickedEpisode[drama.id];
     if (number == null) return fallback;
+    if (fallback.number == number) return fallback;
     for (final episode in drama.episodes) {
       if (episode.number == number) return episode;
     }
@@ -438,6 +439,7 @@ class PlayerLogic extends ChangeNotifier {
           ticket.playUrl,
           likeCount: ticket.likeCount,
           commentCount: ticket.commentCount,
+          thumbnailsUrl: ticket.thumbnailsUrl,
         );
         return true;
       }