Align all internal, exposed, and mapped ports to 8090 universally per user request.

backend/server.js

@@ -177,7 +177,7 @@ app.get('*', (req, res) => {
     res.sendFile(path.join(__dirname, '../public/index.html'));
 });
 
-const PORT = 80;
+const PORT = 8090;
 app.listen(PORT, () => {
     console.log(`Backend server listening on port ${PORT}`);
 });