feat(logging): enhance logging configuration to support environment variable override for log level

backend/app/gateway/app.py

@@ -23,9 +23,11 @@ from app.gateway.routers import (
 )
 from deerflow.config.app_config import get_app_config
 
-# Configure logging
+# Configure logging with env override
+import os
+log_level = os.environ.get("LOG_LEVEL", "INFO").upper()
 logging.basicConfig(
-    level=logging.INFO,
+    level=getattr(logging, log_level, logging.INFO),
     format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
     datefmt="%Y-%m-%d %H:%M:%S",
 )