Restructure the task relay system for better separation of concerns:
- Extract task billing into service/task_billing.go with unified settlement flow
- Move task polling loop from controller to service/task_polling.go (supports Suno + video platforms)
- Split RelayTask into fetch/submit paths with dedicated retry logic (taskSubmitWithRetry)
- Add TaskDto, TaskResponse generics, and FetchReq to dto/task.go
- Add taskcommon/helpers.go for shared task adaptor utilities
- Remove controller/task_video.go (logic consolidated into service layer)
- Update all task adaptors (ali, doubao, gemini, hailuo, jimeng, kling, sora, suno, vertex, vidu)
- Simplify frontend task logs to use new TaskDto response format
* feat: add ali wan video
* refactor: use same UnmarshalBodyReusable
* feat: enhance request body metadata
* feat: opt wan convertToOpenAIVideo
* feat: add wan support other param via json metadata
* refactor: remove unused code
* fix ali
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Co-authored-by: feitianbubu <feitianbubu@qq.com>
