UTen R2 Worker · OK

POST /upload?key=foo.png  (header X-Uten-Token)
GET  /file/:key            (public)
GET  /proxy?url=<火山视频>  (public · 加 CORS 回流，ai-anim 末帧续接用)
POST /img/submit           (Bearer 登录JWT · ai-anim 生图代理→apimart)
GET  /img/task/:id         (Bearer 登录JWT · 查生图任务)
DELETE /file/:key          (header X-Uten-Token)