feat (api): priority property on actions

gmus-backend/pkg/server/actions.go

@@ -20,6 +20,7 @@ const (
 type Action struct {
 	Type       ActionType  `json:"type"`
 	FromClient *string     `json:"fromClient"`
+	Priority   *int        `json:"priority"`
 	Payload    interface{} `json:"payload"`
 }