查询视频生成任务

{
  "id": "task_123456",
  "task_id": "task_123456",
  "object": "video",
  "model": "doubao-seedance-2-0-260128",
  "status": "completed",
  "progress": 100,
  "created_at": 1760000000,
  "completed_at": 1760000020,
  "metadata": {
    "url": "https://example.com/output.mp4"
  },
  "error": {
    "message": "upstream error message",
    "code": "upstream_error_code"
  }
}

{
  "error": null,
  "message": "success"
}