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

service/log_info_generate.go

@@ -204,7 +204,7 @@ func GenerateClaudeOtherInfo(ctx *gin.Context, relayInfo *relaycommon.RelayInfo,
 	return info
 }
 
-func GenerateMjOtherInfo(relayInfo *relaycommon.RelayInfo, priceData types.PerCallPriceData) map[string]interface{} {
+func GenerateMjOtherInfo(relayInfo *relaycommon.RelayInfo, priceData types.PriceData) map[string]interface{} {
 	other := make(map[string]interface{})
 	other["model_price"] = priceData.ModelPrice
 	other["group_ratio"] = priceData.GroupRatioInfo.GroupRatio