fix: update Express wildcard route for path-to-regexp v8 compatibility

server.js

@@ -54,7 +54,7 @@ app.post('/api/chat/stream', async (req, res) => {
 });
 
 // SPA fallback - all other routes serve index.html
-app.get('*', (req, res) => {
+app.get('/*', (req, res) => {
   res.sendFile(path.join(__dirname, 'dist', 'index.html'));
 });