fix: use structlog instead of logging in mem0_manager for kwargs support

backend/mem0_manager.py

@@ -12,11 +12,12 @@ from tenacity import (
     retry_if_exception_type,
     before_sleep_log,
 )
+import structlog
 
 from config import settings
 from monitoring import timed
 
-logger = logging.getLogger(__name__)
+logger = structlog.get_logger(__name__)
 
 # Retry decorator for database operations (Qdrant, Neo4j)
 db_retry = retry(