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/users.ts

@@ -0,0 +1,56 @@
+import client from './client';
+import type { UserInfo } from './auth';
+
+export interface PaginatedResponse<T> {
+  data: T[];
+  total: number;
+  page: number;
+  page_size: number;
+  total_pages: number;
+}
+
+export interface CreateUserRequest {
+  username: string;
+  password: string;
+  email?: string;
+  phone?: string;
+  display_name?: string;
+}
+
+export interface UpdateUserRequest {
+  email?: string;
+  phone?: string;
+  display_name?: string;
+  status?: string;
+}
+
+export async function listUsers(page = 1, pageSize = 20) {
+  const { data } = await client.get<{ success: boolean; data: PaginatedResponse<UserInfo> }>(
+    '/users',
+    { params: { page, page_size: pageSize } }
+  );
+  return data.data;
+}
+
+export async function getUser(id: string) {
+  const { data } = await client.get<{ success: boolean; data: UserInfo }>(`/users/${id}`);
+  return data.data;
+}
+
+export async function createUser(req: CreateUserRequest) {
+  const { data } = await client.post<{ success: boolean; data: UserInfo }>('/users', req);
+  return data.data;
+}
+
+export async function updateUser(id: string, req: UpdateUserRequest) {
+  const { data } = await client.put<{ success: boolean; data: UserInfo }>(`/users/${id}`, req);
+  return data.data;
+}
+
+export async function deleteUser(id: string) {
+  await client.delete(`/users/${id}`);
+}
+
+export async function assignRoles(userId: string, roleIds: string[]) {
+  await client.post(`/users/${userId}/roles`, { role_ids: roleIds });
+}