Load Turnstile site key at runtime

backend/routes/authRoutes.js

@@ -1,6 +1,6 @@
 const express = require('express');
 const { login } = require('../auth');
-const { TURNSTILE_SECRET } = require('../config');
+const { TURNSTILE_SECRET, TURNSTILE_SITE_KEY } = require('../config');
 
 const router = express.Router();
 const TURNSTILE_VERIFY_URL = 'https://challenges.cloudflare.com/turnstile/v0/siteverify';
@@ -34,6 +34,13 @@ const verifyCaptcha = async (captchaToken, remoteIp) => {
     }
 };
 
+router.get('/login/config', (req, res) => {
+    res.json({
+        captchaRequired: Boolean(TURNSTILE_SECRET),
+        turnstileSiteKey: TURNSTILE_SITE_KEY
+    });
+});
+
 router.post('/login', async (req, res, next) => {
     const { email, password, captchaToken } = req.body;