Add auth middleware

backend/src/middleware/auth.js

@@ -0,0 +1,25 @@
+const jwt = require('jsonwebtoken');
+const { db } = require('../database/db');
+
+async function adminAuth(req, res, next) {
+  try {
+    const token = req.headers.authorization?.split(' ')[1];
+    if (!token) {
+      return res.status(401).json({ error: 'No token provided' });
+    }
+    
+    const decoded = jwt.verify(token, process.env.JWT_SECRET);
+    const admin = await db('admin_users').where({ id: decoded.id, is_active: true }).first();
+    
+    if (!admin) {
+      return res.status(401).json({ error: 'Invalid token' });
+    }
+    
+    req.admin = admin;
+    next();
+  } catch (error) {
+    res.status(401).json({ error: 'Invalid token' });
+  }
+}
+
+module.exports = { adminAuth };