refactor: Remove unused HTTPException imports from routers

After removing all try/except blocks that used HTTPException for domain
exception conversion, these imports are no longer needed in the routers.

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

backend/app/routers/server.py

@@ -10,12 +10,11 @@ to flush log files.
 
 from __future__ import annotations
 
-from fastapi import APIRouter, HTTPException, Request, status
+from fastapi import APIRouter, Request, status
 
 from app.dependencies import AuthDep, Fail2BanSocketDep
 from app.models.server import ServerSettingsResponse, ServerSettingsUpdate
 from app.services import server_service
-from app.exceptions import ServerOperationError, Fail2BanConnectionError
 
 router: APIRouter = APIRouter(prefix="/api/server", tags=["Server"])