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
Aligns the error variable types in the subscription-first path so that quota fallback checks use the correct NewAPIError.
This prevents build failures and preserves the intended wallet fallback when subscription pre-consume returns an insufficient quota error.
Add a lightweight active-subscription check to skip subscription pre-consume when none exist, reducing unnecessary transactions and locks. In the subscription UI, disable subscription-first options when no active plan is available, show the effective fallback to wallet with a clear notice, and distinguish “invalidated” from “expired” states. Update i18n strings across supported locales to reflect the new messages and status labels.
