Services no longer receive the concrete account store. on_command now takes
&mut dyn Store + &dyn NetView (both defined in fedserv-api); the engine's Db
and Network implement them. Reads hand back plain views (AccountView,
ChannelView, ...) carrying only non-secret fields, so the event log, gossip,
and credential material (password hash, SCRAM verifiers) are unreachable from
a module. All command modules ported; behaviour unchanged.
When email is configured and a REGISTER includes an address, the account
starts unverified and a confirmation code is emailed. CONFIRM <code>
verifies it (a federated AccountVerified event); INFO shows an unconfirmed
email until then. Emailed codes now carry a purpose (reset vs confirm).
INFO shows an account's registration date and (to its owner) email; ALIST
lists the channels an account founds or has access on. The UTC time
formatter moves to the db module so both services share it.
