add initial component tests [WIP]

[mr-zwets]

No description provided.

[rnbrady]

Nice work. Two thoughts:

1. Some test libraries encourage testing what the user expects rather than what the developer expects. This avoids adding lots of testing labels. A somewhat trivial example:

2. Having two vitest config files is a bit of a kludge. I think this was standard practice with vitest v3 but in v4 there's a cleaner way to do it with a single file, which is what I did here:

Because there's no browser.enabled: true in the config, the browser checks won't run by default so you can do:

vitest or
vitest --browser

However in the case of Cashonize perhaps all tests should just run in the browser by default.