Phone-test the Next.js dev server on LAN

A feature working on my laptop for dev at the normal http://localhost:3000 was not working when I loaded up the network url for testing. However the production build was fine.

When you open http://192.168.x.x:3000 from a phone, Next may block /_next dev resources. CSS still loads; React handlers often do not.

Add the LAN host and restart the dev server:

const nextConfig: NextConfig = {
  // ...
  allowedDevOrigins: ["192.168.1.154"],
};

Use your machine's actual LAN IP.