A serverconfig.env (or just environment variables) can be set to
override the default bind address/port for the backend. This is passed
to the front end as a query parameter.
Useful for development if you want to disable API key authentication for
debugging the server without having to pull the generated key out of the
log every time.
A possible explanation for the infrequent CTDs we've been seeing since
adding fast forward is that QWebChannel doesn't keep a reference to the
python objects that it passes to js, so if the object is GC'd before the
front end is done with it, it crashes.
We don't really like QWebChannel anyway, so this begins replacing that
with FastAPI.
