Move Fail2Ban exceptions into central app.exceptions module

backend/app/routers/jail_config.py

@@ -46,7 +46,7 @@ from app.services import (
     filter_config_service,
     jail_config_service,
 )
-from app.utils.fail2ban_client import Fail2BanConnectionError
+from app.exceptions import Fail2BanConnectionError
 from app.utils.runtime_state import (
     clear_activation_record,
     clear_pending_recovery,