Oh right, this previously logic was silly: we can't count on the
*interval itself* to be reliably resetting the FPS counter state,
because the interval might not be firing!
I think this fix worked when I tried brief tests, but didn't work when
I did an (accidental) longer test, because the browser switched to a
more aggressive throttle mode, and the previous mode was close enough
on the resets for it to be fine, whereas this time the FPS counter
state got way too old.
Now, we reset the FPS counter state *exactly* when the page comes back.
We have a feature to check the movie's FPS, and pause it if it gets too
low, as a guard against especially low-performance movies. But this was
triggering in an *expected* case, where browsers intentionally throttle
interval events when a page is in the background (e.g. you switch to
another tab).
Now, our rendering is aware of page visibility: when the page is
hidden, don't bother rendering, and keep resetting the FPS counter
state, so that we can pick up with a fresh FPS counter when the page
comes back.
Looks like the version of Prettier I just installed is v3, whereas our
last run in the impress-2020 repo was with v2. I don't think we had any
special config in that project, I think these are just changes to
Prettier's defaults, and I'm comfortable accepting them! (Mostly seems
like a lot of trailing commas.)
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.
