Refactor response handling and health check endpoints

- Enhance response model with additional fields and validation
- Update health and server router implementations
- Improve frontend type definitions and API integration
- Clean up documentation

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

backend/app/routers/server.py

@@ -14,6 +14,7 @@ from fastapi import APIRouter, Request, status
 
 from app.dependencies import AuthDep, Fail2BanSocketDep
 from app.mappers import server_mappers
+from app.models.response import FlushLogsResponse
 from app.models.server import ServerSettingsResponse, ServerSettingsUpdate
 from app.services import server_service
 
@@ -86,12 +87,13 @@ async def update_server_settings(
     "/flush-logs",
     status_code=status.HTTP_200_OK,
     summary="Flush and re-open fail2ban log files",
+    response_model=FlushLogsResponse,
 )
 async def flush_logs(
     request: Request,
     _auth: AuthDep,
     socket_path: Fail2BanSocketDep,
-) -> dict[str, str]:
+) -> FlushLogsResponse:
     """Flush and re-open fail2ban log files.
 
     Useful after log rotation so the daemon writes to the newly created
@@ -102,11 +104,11 @@ async def flush_logs(
         _auth: Validated session.
 
     Returns:
-        ``{"message": "<response from fail2ban>"}``
+        :class:`~app.models.response.FlushLogsResponse` with the result from fail2ban.
 
     Raises:
         HTTPException: 400 when the command is rejected.
         HTTPException: 502 when fail2ban is unreachable.
     """
     result = await server_service.flush_logs(socket_path)
-    return {"message": result}
+    return FlushLogsResponse(message=result)