fix(memory): call renamed memory count sync method

- Update forgetting cycle call sites to use _sync_memory_count_to_db

api/app/services/memory_dashboard_service.py

@@ -1,5 +1,5 @@
 from sqlalchemy.orm import Session
-from sqlalchemy import desc, nullslast, or_, and_, cast, String, func
+from sqlalchemy import desc, nullslast, or_, cast, String, func
 from typing import List, Optional, Dict, Any
 import uuid
 from fastapi import HTTPException