恢复无 cookie 拉流修复：iPhone 原生播放器（AVPlayer/夸克系统解码）不携带 cookie 时媒体资产可凭会话 ID 拉流，纯 HTTP 生效；新增拉流拒绝诊断日志

internal/app/ui_playback_native.go

@@ -95,10 +95,16 @@ func (app *UIApp) handlePlaybackNativeAsset(writer http.ResponseWriter, request
 		writeJSON(writer, http.StatusBadRequest, map[string]string{"error": "播放请求编号无效"})
 		return
 	}
+	viewer := contextViewer(request.Context())
 	app.playbackMu.Lock()
 	session := app.playbacks[query.Get("session")]
-	if !viewerOwnsPlayback(request.Context(), session) || session.run != run || session.native == nil {
+	denied := session == nil || session.run != run || session.native == nil
+	if !denied && viewer != nil {
+		denied = !viewerOwnsPlayback(request.Context(), session)
+	}
+	if denied {
 		app.playbackMu.Unlock()
+		app.recordPlaybackAssetDenial(request, "stream-unavailable")
 		writeJSON(writer, http.StatusGone, map[string]string{"error": "此播放流已结束，请重新选择分集"})
 		return
 	}