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

controller/relay.go

@@ -451,17 +451,102 @@ func RelayNotFound(c *gin.Context) {
 }
 
 func RelayTask(c *gin.Context) {
-	retryTimes := common.RetryTimes
 	channelId := c.GetInt("channel_id")
 	c.Set("use_channel", []string{fmt.Sprintf("%d", channelId)})
 	relayInfo, err := relaycommon.GenRelayInfo(c, types.RelayFormatTask, nil, nil)
 	if err != nil {
+		c.JSON(http.StatusInternalServerError, &dto.TaskError{
+			Code:       "gen_relay_info_failed",
+			Message:    err.Error(),
+			StatusCode: http.StatusInternalServerError,
+		})
 		return
 	}
-	taskErr := taskRelayHandler(c, relayInfo)
-	if taskErr == nil {
-		retryTimes = 0
+
+	// Fetch 操作是纯 DB 查询（或 task 自带 channelId 的上游查询），不依赖上下文 channel，无需重试
+	// TODO: 在video-route层面优化，避免无谓的 channel 选择和上下文设置，也没必要吧代码放到这里来写这么多屎山
+	switch relayInfo.RelayMode {
+	case relayconstant.RelayModeSunoFetch, relayconstant.RelayModeSunoFetchByID, relayconstant.RelayModeVideoFetchByID:
+		if taskErr := relay.RelayTaskFetch(c, relayInfo.RelayMode); taskErr != nil {
+			respondTaskError(c, taskErr)
+		}
+		return
 	}
+
+	// ── Submit 路径 ─────────────────────────────────────────────────
+
+	// 1. 解析原始任务（remix / continuation），一次性，可能锁定渠道并禁止重试
+	if taskErr := relay.ResolveOriginTask(c, relayInfo); taskErr != nil {
+		respondTaskError(c, taskErr)
+		return
+	}
+
+	// 2. defer Refund（全部失败时回滚预扣费）
+	var result *relay.TaskSubmitResult
+	var taskErr *dto.TaskError
+	defer func() {
+		if taskErr != nil && relayInfo.Billing != nil {
+			relayInfo.Billing.Refund(c)
+		}
+	}()
+
+	// 3. 执行 + 重试（RelayTaskSubmit 内部在首次调用时自动预扣费）
+	taskErr = taskSubmitWithRetry(c, relayInfo, channelId, common.RetryTimes, func() *dto.TaskError {
+		var te *dto.TaskError
+		result, te = relay.RelayTaskSubmit(c, relayInfo)
+		return te
+	})
+
+	// 4. 成功：结算 + 日志 + 插入任务
+	if taskErr == nil {
+		if settleErr := service.SettleBilling(c, relayInfo, result.Quota); settleErr != nil {
+			common.SysError("settle task billing error: " + settleErr.Error())
+		}
+		service.LogTaskConsumption(c, relayInfo, result.ModelName)
+
+		task := model.InitTask(result.Platform, relayInfo)
+		task.PrivateData.UpstreamTaskID = result.UpstreamTaskID
+		task.PrivateData.BillingSource = relayInfo.BillingSource
+		task.PrivateData.SubscriptionId = relayInfo.SubscriptionId
+		task.PrivateData.TokenId = relayInfo.TokenId
+		task.Quota = result.Quota
+		task.Data = result.TaskData
+		task.Action = relayInfo.Action
+		if insertErr := task.Insert(); insertErr != nil {
+			//taskErr = service.TaskErrorWrapper(insertErr, "insert_task_failed", http.StatusInternalServerError)
+			common.SysError("insert task error: " + insertErr.Error())
+		}
+	}
+
+	if taskErr != nil {
+		respondTaskError(c, taskErr)
+	}
+}
+
+// respondTaskError 统一输出 Task 错误响应（含 429 限流提示改写）
+func respondTaskError(c *gin.Context, taskErr *dto.TaskError) {
+	if taskErr.StatusCode == http.StatusTooManyRequests {
+		taskErr.Message = "当前分组上游负载已饱和，请稍后再试"
+	}
+	c.JSON(taskErr.StatusCode, taskErr)
+}
+
+// taskSubmitWithRetry 执行首次尝试并在失败时切换渠道重试，返回最终的 taskErr。
+// attempt 闭包负责实际的上游请求，不涉及计费。
+func taskSubmitWithRetry(c *gin.Context, relayInfo *relaycommon.RelayInfo,
+	channelId int, retryTimes int, attempt func() *dto.TaskError) *dto.TaskError {
+
+	taskErr := attempt()
+	if taskErr == nil {
+		return nil
+	}
+	if !taskErr.LocalError {
+		processChannelError(c,
+			*types.NewChannelError(channelId, c.GetInt("channel_type"), c.GetString("channel_name"), common.GetContextKeyBool(c, constant.ContextKeyChannelIsMultiKey),
+				common.GetContextKeyString(c, constant.ContextKeyChannelKey), common.GetContextKeyBool(c, constant.ContextKeyChannelAutoBan)),
+			types.NewOpenAIError(taskErr.Error, types.ErrorCodeBadResponseStatusCode, taskErr.StatusCode))
+	}
+
 	retryParam := &service.RetryParam{
 		Ctx:        c,
 		TokenGroup: relayInfo.TokenGroup,
@@ -480,7 +565,7 @@ func RelayTask(c *gin.Context) {
 		useChannel = append(useChannel, fmt.Sprintf("%d", channelId))
 		c.Set("use_channel", useChannel)
 		logger.LogInfo(c, fmt.Sprintf("using channel #%d to retry (remain times %d)", channel.Id, retryParam.GetRetry()))
-		//middleware.SetupContextForSelectedChannel(c, channel, originalModel)
+		middleware.SetupContextForSelectedChannel(c, channel, c.GetString("original_model"))
 
 		bodyStorage, err := common.GetBodyStorage(c)
 		if err != nil {
@@ -492,30 +577,21 @@ func RelayTask(c *gin.Context) {
 			break
 		}
 		c.Request.Body = io.NopCloser(bodyStorage)
-		taskErr = taskRelayHandler(c, relayInfo)
+		taskErr = attempt()
+		if taskErr != nil && !taskErr.LocalError {
+			processChannelError(c,
+				*types.NewChannelError(channel.Id, channel.Type, channel.Name, channel.ChannelInfo.IsMultiKey,
+					common.GetContextKeyString(c, constant.ContextKeyChannelKey), channel.GetAutoBan()),
+				types.NewOpenAIError(taskErr.Error, types.ErrorCodeBadResponseStatusCode, taskErr.StatusCode))
+		}
 	}
+
 	useChannel := c.GetStringSlice("use_channel")
 	if len(useChannel) > 1 {
 		retryLogStr := fmt.Sprintf("重试：%s", strings.Trim(strings.Join(strings.Fields(fmt.Sprint(useChannel)), "->"), "[]"))
 		logger.LogInfo(c, retryLogStr)
 	}
-	if taskErr != nil {
-		if taskErr.StatusCode == http.StatusTooManyRequests {
-			taskErr.Message = "当前分组上游负载已饱和，请稍后再试"
-		}
-		c.JSON(taskErr.StatusCode, taskErr)
-	}
-}
-
-func taskRelayHandler(c *gin.Context, relayInfo *relaycommon.RelayInfo) *dto.TaskError {
-	var err *dto.TaskError
-	switch relayInfo.RelayMode {
-	case relayconstant.RelayModeSunoFetch, relayconstant.RelayModeSunoFetchByID, relayconstant.RelayModeVideoFetchByID:
-		err = relay.RelayTaskFetch(c, relayInfo.RelayMode)
-	default:
-		err = relay.RelayTaskSubmit(c, relayInfo)
-	}
-	return err
+	return taskErr
 }
 
 func shouldRetryTaskRelay(c *gin.Context, channelId int, taskErr *dto.TaskError, retryTimes int) bool {