Three surfaces were showing generated identicons: the forge org avatar
(which is what Discord unfurls), the GitHub org avatar, and the browser
tab, because the app shipped no favicon at all.
make_icons.py turns one SVG or PNG into the seven sizes plus a
multi-resolution favicon.ico. The server now serves /favicon.ico and
/icons/*.png from icons/ when they exist, and index.html asks for them,
so dropping the real mark into icons/ is the whole integration.
Co-developed-with: CLU <clu@binaryranch.com>
