Test published web apps from other devices on the local network

When Publish creates a local test build of a web app (Publish > Test on this computer), the Start Test button serves it on a private loopback address, so only browsers on the same computer can open it. Testing on a phone or tablet today means starting the published executable manually from a terminal with --urls.

Add an option to Start Test that also serves the app on the local network, so a phone, tablet, or another computer on the same Wi-Fi can open it at the address shown in the results window. This makes it easy to test responsive layouts, touch behaviour, and real mobile browsers before deploying anywhere.