feat: add backend infrastructure - Express server, auth, CRUD APIs, DB migrations

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

src/middleware/auth.js

@@ -0,0 +1,29 @@
+const jwt = require('jsonwebtoken');
+
+function authenticateToken(req, res, next) {
+  const authHeader = req.headers['authorization'];
+  const token = authHeader && authHeader.split(' ')[1];
+  
+  if (!token) {
+    return res.status(401).json({ error: 'Access token required' });
+  }
+  
+  jwt.verify(token, process.env.JWT_SECRET || 'changeme', (err, user) => {
+    if (err) {
+      return res.status(403).json({ error: 'Invalid or expired token' });
+    }
+    req.user = user;
+    next();
+  });
+}
+
+function requireRole(...roles) {
+  return (req, res, next) => {
+    if (!req.user || !roles.includes(req.user.role)) {
+      return res.status(403).json({ error: 'Insufficient permissions' });
+    }
+    next();
+  };
+}
+
+module.exports = { authenticateToken, requireRole };