fix: use sublayer instead of replacing NSView backing layer to prevent autorelease crash

- PlayerNSView: AVPlayerLayer as sublayer (not layer= replacement)
  NSView internally manages a sublayer array; replacing the backing
  layer directly causes dangling refs during autorelease pool drain
- cleanup(): only pause + remove observers, no replaceCurrentItem
  CoreMedia internal state gets corrupted when item is replaced
  during view teardown; let it release naturally with deinit

Sources/PlayerBridge.swift

@@ -388,12 +388,13 @@ final class PlayerBridge: ObservableObject {
     
     /// 主动清理所有观察者，在 app 退出前调用
     func cleanup() {
+        player.pause()
         if let obs = timeObserver { player.removeTimeObserver(obs); timeObserver = nil }
         itemStatusObserver?.invalidate(); itemStatusObserver = nil
         playbackStatusObserver?.invalidate(); playbackStatusObserver = nil
         if let token = endObserverToken { NotificationCenter.default.removeObserver(token); endObserverToken = nil }
-        player.pause()
-        player.replaceCurrentItem(with: nil)
+        // 注意：不调用 replaceCurrentItem(with: nil)
+        // 让 playerItem 随 player 自然释放，避免 CoreMedia 内部状态不一致
     }
     
     deinit {

Sources/VideoPlayerView.swift

@@ -54,26 +54,29 @@ struct VideoPlayerRepresentable: NSViewRepresentable {
 }
 
 class PlayerNSView: NSView {
+    private let playerLayer = AVPlayerLayer()
+    
     override init(frame: NSRect) {
         super.init(frame: frame)
         wantsLayer = true
-        let playerLayer = AVPlayerLayer()
         playerLayer.videoGravity = .resizeAspect
-        layer = playerLayer
     }
     
-    required init?(coder: NSCoder) {
-        fatalError()
-    }
+    required init?(coder: NSCoder) { fatalError() }
     
     override func layout() {
         super.layout()
-        (layer as? AVPlayerLayer)?.frame = bounds
+        // 确保 playerLayer 作为 sublayer 存在（不要在 init 中 addSublayer，
+        // 因为 wantsLayer=true 后 layer 可能还没创建）
+        if playerLayer.superlayer !== layer {
+            layer?.addSublayer(playerLayer)
+        }
+        playerLayer.frame = bounds
     }
     
     var player: AVPlayer? {
-        get { (layer as? AVPlayerLayer)?.player }
-        set { (layer as? AVPlayerLayer)?.player = newValue }
+        get { playerLayer.player }
+        set { playerLayer.player = newValue }
     }
 }
 #endif