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/suno.go

@@ -4,10 +4,6 @@ import (
 	"encoding/json"
 )
 
-type TaskData interface {
-	SunoDataResponse | []SunoDataResponse | string | any
-}
-
 type SunoSubmitReq struct {
 	GptDescriptionPrompt string  `json:"gpt_description_prompt,omitempty"`
 	Prompt               string  `json:"prompt,omitempty"`
@@ -20,10 +16,6 @@ type SunoSubmitReq struct {
 	MakeInstrumental     bool    `json:"make_instrumental"`
 }
 
-type FetchReq struct {
-	IDs []string `json:"ids"`
-}
-
 type SunoDataResponse struct {
 	TaskID     string          `json:"task_id" gorm:"type:varchar(50);index"`
 	Action     string          `json:"action" gorm:"type:varchar(40);index"` // 任务类型, song, lyrics, description-mode
@@ -66,30 +58,6 @@ type SunoLyrics struct {
 	Text   string `json:"text"`
 }
 
-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 {
-	TaskID     string          `json:"task_id"` // 第三方id，不一定有/ song id\ Task id
-	Action     string          `json:"action"`  // 任务类型, song, lyrics, description-mode
-	Status     string          `json:"status"`  // 任务状态, submitted, queueing, processing, success, failed
-	FailReason string          `json:"fail_reason"`
-	SubmitTime int64           `json:"submit_time"`
-	StartTime  int64           `json:"start_time"`
-	FinishTime int64           `json:"finish_time"`
-	Progress   string          `json:"progress"`
-	Data       json.RawMessage `json:"data"`
-}
-
 type SunoGoAPISubmitReq struct {
 	CustomMode bool `json:"custom_mode"`