fix(admin): correct 401 redirect path to include /admin prefix

The API interceptor was redirecting to /login on 401 errors, but since
admin-client is deployed under /admin/, it should redirect to /admin/login.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/admin-client/src/shared/utils/api.ts

@@ -28,7 +28,7 @@ api.interceptors.response.use(
   (error) => {
     if (error.response?.status === 401) {
       localStorage.removeItem('admin_token');
-      window.location.href = '/login';
+      window.location.href = '/admin/login';
     }
     return Promise.reject(error);
   }