视频仿制 Video Replicate

Video replicate tool: extracts the first frame and audio from the source video, runs video understanding for a prompt, and returns a Seedance 2.0 replicate bundle (first frame + audio + video). 视频复刻工具，从源视频中提取首帧与音频，并通过视频理解生成描述提示，输出 Seedance 2.0 复刻方案（首帧 + 音频 + 视频）三件套。