Migrate vue-cli to vite

[jeffsmohan]

Why is this issue important?

This is a frontend engineering infrastructure migration as part of decision 0008. Migrate to Vite. This should improve developer experience and pave the way for an easier migration to Vue 3.

Testing implications

This code change should not introduce any behavior change to the site (aside from relatively invisible things, like different chunking of deployed files and minification strategies, which if anything should make the site load a very-likely-not-noticeable tiny bit faster).

To test this on staging, we should do a quick run-through of all basic site functionality to ensure it remains unchanged. Specifically, we should pay attention to anything a bit more "infra-y", like:

• Ensure the page titles (what shows up in the browser tab) are correct
• Ensure the favicon still works
• Check that all images and other static assets (e.g., downloadable spreadsheet templates) load correctly

[ClaireValdivia]

I've tested core workflows in staging with attention to the items you listed above, and everything is looking good to me!