获取视频生成任务状态

{
    "task_id": "abcd1234efgh",
    "status": "queued",
    "url": "https://example.com/video.mp4",
    "format": "mp4",
    "metadata": {
        "duration": 5,
        "fps": 30,
        "width": 1280,
        "height": 720,
        "seed": 20231234
    },
    "error": {
        "code": 0,
        "message": "string"
    }
}