ChanServ sends FMODE to mark a registered channel +r (the m_services
c_registered mode), and -r on drop. Sourced from our server, which the
ircd requires for that mode, with a low TS so it applies to the existing
channel.
REGISTER/INFO/DROP with founder auth, stored as ChannelRegistered and
ChannelDropped events so channel registrations replicate across nodes
and compact like accounts. Registration requires an identified account;
only the founder can drop.
