fix(06.2): CR-03 serialize metadata_ with json.dumps in CSV export instead of Python repr

backend/api/audit.py

@@ -23,6 +23,7 @@ from __future__ import annotations
 import asyncio
 import csv
 import io
+import json
 import re
 import uuid
 from datetime import datetime
@@ -371,7 +372,9 @@ async def export_audit_log(
     writer.writeheader()
     for row in rows:
         entry, user_handle_val, actor_handle_val = row[0], row[1], row[2]
-        writer.writerow(_audit_to_dict_with_handles(entry, user_handle_val, actor_handle_val))
+        record = _audit_to_dict_with_handles(entry, user_handle_val, actor_handle_val)
+        record["metadata_"] = json.dumps(record["metadata_"]) if record["metadata_"] is not None else ""
+        writer.writerow(record)
 
     return StreamingResponse(
         iter([output.getvalue()]),