I haven't been running Prettier consistently on things in this project.
Now, it's quick-runnable, and I've got it on everything!
Also, I just think tabs are the right default for this kind of thing,
and I'm glad to get to switch over to it! (In `package.json`.)
We add jsbuilding-rails to get esbuild running in the app, and then we copy-paste the files we need from impress-2020 into here!
I stopped at the point where it was building successfully, but it's not running correctly: it's not sure about `process.env` in `next`, and I think the right next step is to delete the NextJS deps altogether and use React Router instead.
