This is a big change, but I think it's a good move, as `vitest` is much
more modern than `jest`.
I'm excited about the UI watch feature (run `npm run test:ui`), for
example - it's really helpful and saves time when debugging tests. I had
to adjust a few tests because they had time related issues, but
basically we are now testing the same things - even a bit better and
less flaky (I hope).
What do you think?
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