feat(web): add login and register pages with auth store

- API client with token refresh interceptor
- Auth API functions (login, register, logout, getMe)
- Auth store with Zustand persistence
- Auth layout with centered card design
- Login page with form validation
- Register page with company and user data
- Environment example file

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

apps/web/lib/api/auth.ts

@@ -0,0 +1,22 @@
+import { apiClient } from './client';
+import type { LoginRequest, RegisterRequest, LoginResponse } from '@horux/shared';
+
+export async function login(data: LoginRequest): Promise<LoginResponse> {
+  const response = await apiClient.post<LoginResponse>('/auth/login', data);
+  return response.data;
+}
+
+export async function register(data: RegisterRequest): Promise<LoginResponse> {
+  const response = await apiClient.post<LoginResponse>('/auth/register', data);
+  return response.data;
+}
+
+export async function logout(): Promise<void> {
+  const refreshToken = localStorage.getItem('refreshToken');
+  await apiClient.post('/auth/logout', { refreshToken });
+}
+
+export async function getMe(): Promise<LoginResponse['user']> {
+  const response = await apiClient.get('/auth/me');
+  return response.data.user;
+}