refactor: enhance Optuna backtesting framework, optimize orderbook filtering, and update database management utilities.

kis_trader/backtest/optuna_common.py

@@ -546,7 +546,7 @@ def ensure_optuna_database(db_name: Optional[str] = None) -> str:
                     creds["user"], creds["host"], creds["port"], name,
                 )
             else:
-                logger.info(
+                logger.debug(
                     "📦 Optuna storage DB: %s@%s:%s/%s",
                     creds["user"], creds["host"], creds["port"], name,
                 )