After trying to upload an especially large video, I crashed the site so hard it died. Based on the errors I got after trying to start it, I was able to determine that it was unable to connect to mysql, but I was able to connect to mysql manually just fine.
It seemed like no matter what I tried to change in mysql, nothing changed so ultimately I decided to just fully reinstall, which I assumed would wipe all of the data, which I would then restore from a backup. However, after reinstalling mysql and running ghost setup, it just magically worked, and astonishingly all the data was still there.
Happy end, I guess?