Adds idempotent root-folder bootstrap (Clients/Companies/Yachts)
called on every port-init. ON CONFLICT DO NOTHING on the sibling-name
unique index prevents racing inserts; the re-SELECT returns the stable
row set in SYSTEM_ROOT_NAMES order. Same helper is invoked by the
backfill script in a later task.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>