Move Fail2Ban exceptions into central app.exceptions module

backend/tests/test_services/test_health_service.py

@@ -9,7 +9,7 @@ import pytest
 
 from app.models.server import ServerStatus
 from app.services import health_service
-from app.utils.fail2ban_client import Fail2BanConnectionError, Fail2BanProtocolError
+from app.exceptions import Fail2BanConnectionError, Fail2BanProtocolError
 
 # ---------------------------------------------------------------------------
 # Helpers