add agent completion API (#3192)

### What problem does this PR solve?

#3105

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

api/db/services/canvas_service.py

@@ -22,5 +22,6 @@ from api.db.services.common_service import CommonService
 class CanvasTemplateService(CommonService):
     model = CanvasTemplate
 
+
 class UserCanvasService(CommonService):
     model = UserCanvas