Twelve more methods, so the registry owns 50 of 113. rpc-host.ts is down from 1332
lines to 830 and the deps factory from 944 to 500.
trips.update keeps its two field-level gates: archiving and changing the cover each
need their own admin-configurable permission on top of trip_edit, so a plugin
cannot do either on a trip it may otherwise edit. Member management keeps its own
grant for the same kind of reason, since adding a member grants trip access, and
the owner still cannot be removed through it because that would orphan the trip.
canEditTrip stays in HostDeps for now: the db:meta gate still resolves an entity's
edit permission through it and has not moved yet.
Maurice