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.
Tracks channel membership (join/part/kick), the current key, and per-nick
last-seen in the network view. Entry messages greet joiners; enforce
re-applies the lock, access modes and auto-kicks to everyone present;
getkey reports the key; seen reports last activity; clone copies a
channel's settings; aop/sop/vop are tiered shortcuts over the access list.
