improve: use react-query for caching

api/markdown.py

@@ -31,7 +31,7 @@ def get_index(path_id):
     with get_db() as session:
         markdown = session.query(Markdown).filter(Markdown.path_id == path_id).filter(Markdown.title == "index").first()
         if markdown is None:
-            return jsonify({"error": "index not exist"}), 404
+            return jsonify({}), 204
         return jsonify(markdown.to_dict()), 200