fix(mui): drop loading state on Users delete dialog (normal close, matches Vozidla)

Per request: the delete ConfirmDialog no longer shows the in-flight 'Pracuji…'/disabled state — button stays 'Smazat' and the dialog closes on success, consistent with the Vozidla delete. The kit ConfirmDialog still supports loading for callers that want it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/Users.tsx

@@ -479,7 +479,6 @@ export default function Users() {
         }
         confirmText="Smazat"
         confirmVariant="danger"
-        loading={deleteUser.isPending}
       />
     </Box>
   );