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

dto/task.go

@@ -1,5 +1,9 @@
 package dto
 
+import (
+	"encoding/json"
+)
+
 type TaskError struct {
 	Code       string `json:"code"`
 	Message    string `json:"message"`
@@ -8,3 +12,46 @@ type TaskError struct {
 	LocalError bool   `json:"-"`
 	Error      error  `json:"-"`
 }
+
+type TaskData interface {
+	SunoDataResponse | []SunoDataResponse | string | any
+}
+
+const TaskSuccessCode = "success"
+
+type TaskResponse[T TaskData] struct {
+	Code    string `json:"code"`
+	Message string `json:"message"`
+	Data    T      `json:"data"`
+}
+
+func (t *TaskResponse[T]) IsSuccess() bool {
+	return t.Code == TaskSuccessCode
+}
+
+type TaskDto struct {
+	ID         int64           `json:"id"`
+	CreatedAt  int64           `json:"created_at"`
+	UpdatedAt  int64           `json:"updated_at"`
+	TaskID     string          `json:"task_id"`
+	Platform   string          `json:"platform"`
+	UserId     int             `json:"user_id"`
+	Group      string          `json:"group"`
+	ChannelId  int             `json:"channel_id"`
+	Quota      int             `json:"quota"`
+	Action     string          `json:"action"`
+	Status     string          `json:"status"`
+	FailReason string          `json:"fail_reason"`
+	ResultURL  string          `json:"result_url,omitempty"` // 任务结果 URL（视频地址等）
+	SubmitTime int64           `json:"submit_time"`
+	StartTime  int64           `json:"start_time"`
+	FinishTime int64           `json:"finish_time"`
+	Progress   string          `json:"progress"`
+	Properties any             `json:"properties"`
+	Username   string          `json:"username,omitempty"`
+	Data       json.RawMessage `json:"data"`
+}
+
+type FetchReq struct {
+	IDs []string `json:"ids"`
+}