By default fedserv owns accounts itself — nothing changes, no external
service required. Set [auth] external = true and an outside authority (the
website) owns identity instead: NickServ REGISTER / DROP / SET
PASSWORD|EMAIL / RESETPASS / CONFIRM / CERT / GROUP and the IRCv3
registration relay are all refused ("managed on the website"), so IRC
can't mint or change a second identity. Login is unchanged — fedserv still
authenticates locally against the accounts the authority pushes in via the
existing gRPC Accounts API, so lookups stay in-memory fast.
fedserv keeps owning all IRC-domain data (channels, access, vhosts, bans,
memos) keyed by the account name in both modes. One config bool, off by
default, so standalone deployments are unaffected.