Load flask_migrate extension in dev/cli mode

backend/app.py

@@ -110,7 +110,11 @@ else:
         logging.info("Running initialization code (dev mode).")
         init_routines()
     else:
-        logging.info("Not running initialization code (dev mode).")
+        logging.info("Not running initialization code (dev or cli mode).")
+        # This should not perform any actual migration, just load the
+        # flask_migrate extension so we can use `flask db` commands from the
+        # cli.
+        flask_migrate.Migrate(app, db)
 
 app.register_blueprint(api_v1)
 app.register_blueprint(web)