change user_name still used as login and add display_name for dashboard view instead of username on login

services/__tests__/apiClient.test.ts

@@ -42,7 +42,7 @@ describe('apiClient', () => {
 
   it('sends CSRF token on POST', async () => {
     document.cookie = 'csrftoken=abc123; path=/';
-    const fetchMock = vi.fn().mockResolvedValue(jsonResponse({ id: 1, user_name: 'admin' }));
+    const fetchMock = vi.fn().mockResolvedValue(jsonResponse({ id: 1, user_name: 'admin', display_name: 'admin' }));
     vi.stubGlobal('fetch', fetchMock);
 
     await api.auth.login('admin', 'admin123');

services/apiClient.ts

@@ -159,8 +159,8 @@ const del = (path: string) => request<void>(path, { method: 'DELETE' });
 export const api = {
   auth: {
     csrf: () => get<{ csrfToken: string }>('/auth/csrf/'),
-    login: (user_login: string, password: string) =>
-      post<User>('/auth/login/', { user_login, password }),
+    login: (user_name: string, password: string) =>
+      post<User>('/auth/login/', { user_name, password }),
     logout: () => post<void>('/auth/logout/'),
     me: () => get<User>('/auth/me/'),
   },