fix: windows start script

backend/start_windows.bat

@@ -28,7 +28,7 @@ SET "WEBUI_SECRET_KEY=%WEBUI_SECRET_KEY%"
 SET "WEBUI_JWT_SECRET_KEY=%WEBUI_JWT_SECRET_KEY%"
 
 :: Check if WEBUI_SECRET_KEY and WEBUI_JWT_SECRET_KEY are not set
-IF "%WEBUI_SECRET_KEY%%WEBUI_JWT_SECRET_KEY%" == " " (
+IF "%WEBUI_SECRET_KEY% %WEBUI_JWT_SECRET_KEY%" == " " (
     echo Loading WEBUI_SECRET_KEY from file, not provided as an environment variable.
 
     IF NOT EXIST "%KEY_FILE%" (