Fix back button cycling in Telegram Mini App

Add replace: true to all navigate() calls in useBackButton hooks
Prevents history cycles when navigating back and forth
All 32 admin pages now use navigate(path, { replace: true })
Back button now goes directly to parent without cycling

src/pages/AdminCampaignCreate.tsx

@@ -156,7 +156,7 @@ export default function AdminCampaignCreate() {
   const navigate = useNavigate();
   const queryClient = useQueryClient();
 
-  useBackButton(() => navigate('/admin/campaigns'));
+  useBackButton(() => navigate('/admin/campaigns', { replace: true }));
 
   // Form state
   const [name, setName] = useState('');