lite-screenshots

A reviewer reading a CSS diff cannot see the result. This captures the Lite UI with the branch applied and again with it unapplied, and posts the surfaces that differ to the pull request.

Capture runs on this machine, not in CI. It was tried in CI and abandoned: under the bare X server on the Linux runners this Electron build paints a frame on load and not reliably afterwards, so several surfaces hung indefinitely whether the capture went through Playwright or the DevTools protocol. The same spec passes here. The CI workflow only leaves a reminder.

Before capturing: is the surface covered?

Work this out first, by reading the diff — not by capturing and inferring it from the result. A run that reports "8 surfaces, 0 changed" looks identical whether the change is invisible or whether nothing looked at it.