feat: 登录界面优化与API代理配置

- 移除登录页面的登录/注册切换，只保留登录功能
- 添加API代理配置支持远程访问
- 添加favicon.ico
- 后端CORS配置支持前端访问

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/lib/api.js

@@ -1,4 +1,4 @@
-const API_BASE = ''; // 使用相对路径，同源代理
+const API_BASE = ''; // 使用相对路径
 
 function getAuthHeaders() {
   const token = typeof window !== 'undefined' ? localStorage.getItem('token') : null;
@@ -15,6 +15,12 @@ async function apiCall(url, options = {}) {
     },
   });
 
+  const contentType = res.headers.get('content-type');
+  if (!contentType || !contentType.includes('application/json')) {
+    const text = await res.text();
+    throw new Error(`服务器错误: ${res.status} - ${text.substring(0, 100)}`);
+  }
+
   const data = await res.json();
 
   if (!res.ok) {

frontend/pages/api/[...path].js

@@ -0,0 +1,17 @@
+export default async function handler(req, res) {
+  const { 0: path } = req.query;
+
+  const backendUrl = `http://localhost:3501/${path}`;
+
+  const response = await fetch(backendUrl, {
+    method: req.method,
+    headers: {
+      'Content-Type': 'application/json',
+      ...(req.headers.authorization ? { Authorization: req.headers.authorization } : {}),
+    },
+    body: req.method !== 'GET' && req.method !== 'HEAD' ? JSON.stringify(req.body) : undefined,
+  });
+
+  const data = await response.json();
+  res.status(response.status).json(data);
+}

frontend/pages/login.js

@@ -8,7 +8,6 @@ import { useToast } from '../components/ToastProvider';
 export default function Login() {
   const router = useRouter();
   const { showToast } = useToast();
-  const [isLoginMode, setIsLoginMode] = useState(true);
   const [username, setUsername] = useState('');
   const [password, setPassword] = useState('');
   const [error, setError] = useState('');
@@ -26,13 +25,8 @@ export default function Login() {
     setLoading(true);
 
     try {
-      if (isLoginMode) {
       await login(username, password);
       showToast('登录成功', { tone: 'success' });
-      } else {
-        await register(username, password);
-        showToast('注册成功', { tone: 'success' });
-      }
       router.push('/');
     } catch (err) {
       setError(err.message);
@@ -50,31 +44,8 @@ export default function Login() {
             <div className="auth-logo__mark" aria-hidden="true">
               <Icon name="chart" size={24} />
             </div>
-            <h1>{isLoginMode ? '欢迎回来' : '创建账户'}</h1>
-            <p>{isLoginMode ? '登录后继续记录每一笔收支' : '注册后即可开始管理你的账本'}</p>
-          </div>
-
-          <div className="auth-switch" role="tablist" aria-label="登录或注册">
-            <button
-              type="button"
-              className={isLoginMode ? 'is-active' : ''}
-              onClick={() => {
-                setIsLoginMode(true);
-                setError('');
-              }}
-            >
-              登录
-            </button>
-            <button
-              type="button"
-              className={!isLoginMode ? 'is-active' : ''}
-              onClick={() => {
-                setIsLoginMode(false);
-                setError('');
-              }}
-            >
-              注册
-            </button>
+            <h1>欢迎回来</h1>
+            <p>登录后继续记录每一笔收支</p>
           </div>
 
           {error && <div className="error-msg">{error}</div>}
@@ -110,7 +81,7 @@ export default function Login() {
                   <Icon name="spinner" size={16} className="is-spinning" />
                   处理中...
                 </span>
-              ) : isLoginMode ? '登录' : '注册'}
+              ) : '登录'}
             </button>
           </form>
         </div>

server.js

@@ -6,11 +6,14 @@ const cors = require('cors');
 const path = require('path');
 
 const app = express();
-const PORT = 3500;
+const PORT = 3501;
 const JWT_SECRET = process.env.JWT_SECRET || 'accountbook_secret_key_2024';
 
 // 中间件
-app.use(cors());
+app.use(cors({
+  origin: ['http://localhost:3500', 'http://127.0.0.1:3500'],
+  credentials: true
+}));
 app.use(express.json());
 app.use(express.static(path.join(__dirname, 'public')));
 app.use(express.static(path.join(__dirname, 'frontend/.next')));