refactor(task): extract billing and polling logic from controller to service layer

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

web/src/components/table/task-logs/modals/ContentModal.jsx

@@ -144,8 +144,6 @@ const ContentModal = ({
             maxHeight: '100%',
             objectFit: 'contain',
           }}
-          autoPlay
-          crossOrigin='anonymous'
           onError={handleVideoError}
           onLoadedData={handleVideoLoaded}
           onLoadStart={() => setIsLoading(true)}