We never had a specific reason why we didn't use the router for this I don't think? Not that I wrote down anyway. Let's just switch it over and see what happens!
I mainly did this as a misdiagnosis of the page reload problem fixed in c162864, but it seems like a good idea to try out anyway!
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.
