feat(web): add login page, auth store, API client, and route guard

- API client with axios interceptors: JWT attach + 401 auto-refresh
- Auth store (Zustand): login/logout/loadFromStorage with localStorage
- Login page: gradient background, Ant Design form, error handling
- Home page: dashboard with statistics cards
- App.tsx: PrivateRoute guard, /login route, auth state restoration
- MainLayout: dynamic user display, logout dropdown, menu navigation
- Users API service: CRUD with pagination support

apps/web/src/api/auth.ts

@@ -0,0 +1,52 @@
+import client from './client';
+
+export interface LoginRequest {
+  username: string;
+  password: string;
+}
+
+export interface UserInfo {
+  id: string;
+  username: string;
+  email?: string;
+  phone?: string;
+  display_name?: string;
+  avatar_url?: string;
+  status: string;
+  roles: RoleInfo[];
+}
+
+export interface RoleInfo {
+  id: string;
+  name: string;
+  code: string;
+  description?: string;
+  is_system: boolean;
+}
+
+export interface LoginResponse {
+  access_token: string;
+  refresh_token: string;
+  expires_in: number;
+  user: UserInfo;
+}
+
+export async function login(req: LoginRequest): Promise<LoginResponse> {
+  const { data } = await client.post<{ success: boolean; data: LoginResponse }>(
+    '/auth/login',
+    req
+  );
+  return data.data;
+}
+
+export async function refresh(refreshToken: string): Promise<LoginResponse> {
+  const { data } = await client.post<{ success: boolean; data: LoginResponse }>(
+    '/auth/refresh',
+    { refresh_token: refreshToken }
+  );
+  return data.data;
+}
+
+export async function logout(): Promise<void> {
+  await client.post('/auth/logout');
+}