Adds the berth_reservations service covering the full lifecycle
(pending -> active -> ended/cancelled) with tenant scoping, DB-enforced
exclusivity on the idx_br_active partial unique index, and
client-or-company-member cross-checks for yacht ownership.
- validators: createPending / activate / end / cancel / list schemas
- service: createPending, activate, endReservation, cancel, getById,
listReservations — with narrow 23505/idx_br_active catch that
re-queries the conflicting active reservation
- socket events: berth_reservation:{created,activated,ended,cancelled}
- tests: unit (lifecycle, tenant, membership cross-check),
integration (concurrent-activate ConflictError + re-activate after end)
b1133c4e87