fix: HLS播放加自定义headers + 录制finishWriting错误日志

HLS播放:
- AVURLAsset替代AVPlayerItem(url:)，加Referer/UA headers
- 某些HLS流服务端校验Referer，裸URL请求被拒绝

录制:
- startWriting检查返回值和error
- finishWriting回调打印status/error/frames
- 失败时删除损坏的临时文件，弹出错误提示

Sources/PlayerBridge.swift

@@ -167,7 +167,13 @@ final class PlayerBridge: ObservableObject {
         itemStatusObserver?.invalidate()
         itemStatusObserver = nil
         
-        let playerItem = AVPlayerItem(url: item.url)
+        // 用 AVURLAsset 支持自定义 HTTP headers（某些 HLS 流需要 Referer/UA）
+        let headers: [String: String] = [
+            "Referer": item.url.deletingLastPathComponent().absoluteString,
+            "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 Safari/605.1.15"
+        ]
+        let asset = AVURLAsset(url: item.url, options: ["AVURLAssetHTTPHeaderFieldsKey": headers])
+        let playerItem = AVPlayerItem(asset: asset)
         
         #if os(macOS)
         // 添加 video output 用于录制

Sources/PlayerRecorder.swift

@@ -98,9 +98,16 @@ final class PlayerRecorder: NSObject {
             audioInput = aInput
         }
         
-        writer.startWriting()
+        let success = writer.startWriting()
+        if !success {
+            print("[Recorder] startWriting failed: \(writer.error?.localizedDescription ?? "unknown")")
+            onError?("Cannot start writer: \(writer.error?.localizedDescription ?? "unknown")")
+            return
+        }
+        
         // session 起点为 0，视频和音频都用相对时间戳
         writer.startSession(atSourceTime: .zero)
+        print("[Recorder] Writer started, session at .zero")
         
         // 启动视频抓帧
         isRecording = true
@@ -136,11 +143,16 @@ final class PlayerRecorder: NSObject {
         
         writer?.finishWriting { [weak self] in
             Task { @MainActor in
-                guard let self = self else { return }
+                guard let self = self, let w = self.writer else { return }
-                if let url = self.tempURL {
+                let count = self.captureFrameCount
-                    let count = self.captureFrameCount
+                print("[Recorder] finishWriting status: \(w.status.rawValue), error: \(w.error?.localizedDescription ?? "none"), frames: \(count)")
-                    print("[Recorder] Finish writing: \(count) video frames")
+                if w.status == .completed, let url = self.tempURL {
                     self.showSaveDialog(tempURL: url)
+                } else {
+                    self.onError?("Recording failed: \(w.error?.localizedDescription ?? "unknown (status=\(w.status.rawValue))")")
+                    if let url = self.tempURL {
+                        try? FileManager.default.removeItem(at: url)
+                    }
                 }
             }
         }