Add /preview route serving the ghost preview page

server.js

@@ -35,6 +35,11 @@ app.get('/admin', (_req, res) => {
   res.sendFile(join(__dirname, 'public', 'admin.html'));
 });
 
+// Ghost preview page (admin-gated client-side; ghost list requires a JWT).
+app.get('/preview', (_req, res) => {
+  res.sendFile(join(__dirname, 'public', 'preview.html'));
+});
+
 // JSON error handler (multer + thrown errors).
 app.use((err, _req, res, _next) => {
   console.error(err);