Adds integration test covering:
- idx_yoh_active: only one active ownership row per yacht
- idx_br_active: only one active reservation per berth (non-active rows
are ignored by the partial index)
- Case-insensitive company name uniqueness within a port, with same-name
companies allowed across different ports
Extends tests/helpers/factories.ts with async DB-inserting factories for
ports, clients, berths, yachts (+ ownership history row) and companies.
The new factories use the app's `db` handle so FK and partial unique
indexes are enforced by Postgres. The in-memory data helpers used by
unit tests (makeAuditMeta, makeCreateClientInput, permission helpers)
are preserved.
