Remove broken default_knot_from_handle; require knot in config file
default_knot_from_handle("gazagnaire.org") produced "git.org" instead
of "git.recoil.org" — it split on the first dot, which fails for
two-part domains.
Rather than trying to guess the knot server from the handle, require
it explicitly in the config file ([identity] knot = "git.recoil.org").
The programmatic Config.v constructor still defaults to "git.recoil.org"
for the verse init bootstrapping case.