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.
Adds the remaining moderation and listing commands. Auto-kick masks are
stored in the event log and enforced on join: a matching user is banned
and kicked. Topic and invite are sourced from the ChanServ pseudoclient.
