fix: replace broad except Exception with specific exception types

- jail_service: catch ValueError (fail2ban protocol error) instead of Exception
- health.py: catch AttributeError (not OSError/TypeError) for defensive checks
- ban_service: re-raise programming errors in geo lookup handlers
- server_service: catch Fail2BanConnectionError, Fail2BanProtocolError, ValueError
- config_writer: catch OSError instead of Exception

Programming errors now bubble to global handler instead of being silently caught.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/app/services/server_service.py

@@ -14,7 +14,7 @@ from typing import cast
 
 import structlog
 
-from app.exceptions import ServerOperationError
+from app.exceptions import Fail2BanConnectionError, Fail2BanProtocolError, ServerOperationError
 from app.models.server_domain import DomainServerSettings, DomainServerSettingsResult
 from app.models.server import ServerSettingsUpdate
 from app.utils.constants import FAIL2BAN_SOCKET_TIMEOUT
@@ -79,7 +79,7 @@ async def _safe_get(
     try:
         response = await client.send(command)
         return ok(cast("Fail2BanResponse", response))
-    except Exception:
+    except (Fail2BanConnectionError, Fail2BanProtocolError, ValueError):
         return default