Add `make openzaak-up`, `make openzaak-smoke`, and `make openzaak-down` so
the OpenZaak stack is testable in one command, matching the `make ci`
pattern. openzaak-smoke polls until the API responds, then asserts auth is
enforced (403) and the admin/schema endpoints are reachable (302/200).
Document it in docs/runbooks/openzaak.md (kept out of `make ci` — it's a
heavier, separate check).
Verified: `make openzaak-smoke` is green end-to-end.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>