feat: add utils, error handler and auth middleware

server/middleware/auth.js

@@ -0,0 +1,29 @@
+const jwt = require('jsonwebtoken');
+const { AppError } = require('./errorHandler');
+
+const JWT_SECRET = process.env.JWT_SECRET || 'accountbook_secret_key_2024';
+
+function authenticate(req, res, next) {
+  const token = req.headers.authorization?.split(' ')[1];
+  if (!token) {
+    throw new AppError('请先登录', 401, 'UNAUTHORIZED');
+  }
+
+  try {
+    const decoded = jwt.verify(token, JWT_SECRET);
+    req.userId = decoded.userId;
+    next();
+  } catch (err) {
+    throw new AppError('登录已过期', 401, 'TOKEN_EXPIRED');
+  }
+}
+
+function generateToken(userId) {
+  return jwt.sign({ userId }, JWT_SECRET, { expiresIn: '7d' });
+}
+
+module.exports = {
+  authenticate,
+  generateToken,
+  JWT_SECRET,
+};