refactor: refactor stable diffusion service, add service pool support

api/store/model/sd_job.go

@@ -11,7 +11,6 @@ type SdJob struct {
 	Progress  int
 	Prompt    string
 	Params    string
-	Started   bool
 	CreatedAt time.Time
 }
 

api/store/vo/sd_job.go

@@ -15,5 +15,4 @@ type SdJob struct {
 	Progress  int                `json:"progress"`
 	Prompt    string             `json:"prompt"`
 	CreatedAt time.Time          `json:"created_at"`
-	Started   bool               `json:"started"`
 }