fix: bug in nebula get_by_metadata

Author: CaralHsi

src/memos/graph_dbs/nebular.py

@@ -830,7 +830,8 @@ def get_by_metadata(self, filters: list[dict[str, Any]]) -> list[str]:
 
         def _escape_value(value):
             if isinstance(value, str):
-                return f'"{value}"'
+                escaped = value.replace('"', '\\"')
+                return f'"{escaped}"'
             elif isinstance(value, list):
                 return "[" + ", ".join(_escape_value(v) for v in value) + "]"
             else: