fix(webhooks): mount webhook routes in index.js before verifyCsrf

Webhook routes were only registered in app.js (the test factory) but
not in index.js (the production entry point). POST /api/webhook/*
was therefore falling through to the verifyCsrf middleware and being
rejected with 403 in production.

server/index.js

@@ -84,6 +84,7 @@ const embyRoutes = require('./routes/emby');
 const dashboardRoutes = require('./routes/dashboard');
 const historyRoutes = require('./routes/history');
 const authRoutes = require('./routes/auth');
+const webhookRoutes = require('./routes/webhook');
 const verifyCsrf = require('./middleware/verifyCsrf');
 const { startPoller, POLL_INTERVAL, POLLING_ENABLED } = require('./utils/poller');
 const { validateInstanceUrl } = require('./utils/config');
@@ -252,6 +253,7 @@ function serveIndex(req, res) {
 // ---------------------------------------------------------------------------
 app.use('/api', apiLimiter);
 app.use('/api/auth', authRoutes);
+app.use('/api/webhook', webhookRoutes);
 
 // All routes below this point require CSRF validation on mutating methods
 app.use('/api', verifyCsrf);