refactor backend and persist stock campaign queue

backend/routes/authRoutes.js

@@ -0,0 +1,18 @@
+const express = require('express');
+const { login } = require('../auth');
+
+const router = express.Router();
+
+router.post('/login', (req, res) => {
+    const { email, password } = req.body;
+    const token = login(email, password);
+
+    if (!token) {
+        res.status(401).json({ error: 'Invalid credentials' });
+        return;
+    }
+
+    res.json({ token });
+});
+
+module.exports = router;