opt: make sure the Upscale and Variation task is assign to the same mj service with Image task

api/store/model/mj_job.go

@@ -7,6 +7,7 @@ type MidJourneyJob struct {
 	Type        string
 	UserId      int
 	TaskId      string
+	ChannelId   string
 	MessageId   string
 	ReferenceId string
 	ImgURL      string

api/store/vo/mj_job.go

@@ -6,6 +6,7 @@ type MidJourneyJob struct {
 	Id          uint      `json:"id"`
 	Type        string    `json:"type"`
 	UserId      int       `json:"user_id"`
+	ChannelId   string    `json:"channel_id"`
 	TaskId      string    `json:"task_id"`
 	MessageId   string    `json:"message_id"`
 	ReferenceId string    `json:"reference_id"`