细节优化

backend/app/services/access_log_service.py

@@ -1,6 +1,6 @@
 """访问日志服务。"""
 
-from datetime import datetime, timezone
+from datetime import datetime
 
 from app.models.access_log import AccessLog
 from sqlalchemy.orm import Session
@@ -24,7 +24,7 @@ class AccessLogService:
             knowledge_base_id=knowledge_base_id,
             document_id=document_id,
             path=path,
-            accessed_at=datetime.now(timezone.utc).isoformat(),
+            accessed_at=datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
             user_agent=user_agent[:500] if user_agent else None,
             request_type=request_type,
         )