Automated way to check screenshots diffs from the GH workflow

We now have an amazing GitHub workflow that runs our screenshot tests, upload them as artifacts, and notify when a PR has made visual changes ([example](https://github.com/ankidroid/Anki-Android/pull/21067#issuecomment-4470765465))

The issue is that the process is too manual:
1. download the artifact
2. extract it
3. go down the directory tree to find the "diff files"
4. open them

Any idea, that is safe for the repo, would be welcome

Mike suggested:

> I wonder...looks like gh allows "extensions", maybe a little extension that was like gh screenshots pr 10022 to snag the compare set (if it exists) do the unpack into $TMPDIR (or some secure temp location) and open the folder ?
> https://discord.com/channels/368267295601983490/701922522836369498/1505619761873031372