feat(infra): seed BIG catalogus + JWT client for OpenZaak (refs #2) (#41)

docs/runbooks/openzaak.md

@@ -9,9 +9,32 @@ migrations, the OpenZaak API, and a celery worker.
 ```bash
 make openzaak-up       # start the stack (first run pulls images + migrates: 1-3 min)
 make openzaak-smoke    # start + assert it's up with auth enforced (403/302/200)
+make openzaak-seed     # start + seed the BIG catalogus (idempotent)
 make openzaak-down     # stop and wipe data
 ```
 
+## Seed the BIG catalogus
+
+`make openzaak-seed` brings the stack up and runs `infra/openzaak/seed_catalogus.py`,
+which creates (idempotently, via the ZTC API):
+
+- catalogus **BIG**
+- a lean **BIG-REGISTRATIE** zaaktype (concept; only schema-mandatory fields)
+- a **bsn** eigenschap on it
+
+then confirms the JWT client can list it. See **ADR-0002** for the design (why the
+zaaktype stays a concept, why notifications are disabled, why the API not a fixture).
+
+**JWT client** (provisioned declaratively by `setup_configuration/data.yaml`, **dev only**):
+
+| | |
+|---|---|
+| client_id | `big-reference-seed` |
+| secret | `insecure-dev-secret-change-me` |
+| authorizations | `heeft_alle_autorisaties` (all) |
+
+The seed mints a ZGW JWT (HS256) from these and calls `/catalogi/api/v1/...`.
+
 `make openzaak-smoke` polls until the API responds, then asserts:
 
 | Check | Expected |
@@ -43,8 +66,9 @@ The Makefile auto-points `DOCKER_HOST` at the Podman socket when it exists, so t
 - **Not in `make ci`.** The OpenZaak smoke is a separate, heavier check (large image
   pull + migrations); it is intentionally kept out of `make ci` so the core gate
   stays fast. Run `make openzaak-smoke` when you touch the OpenZaak stack.
-- **No catalogus/zaaktypen yet.** Seeding the `BIG` catalogus + `BIG-registratie`
-  zaaktype and a JWT client is the next slice (**S-01-b**); authenticated zaaktype
-  listing isn't testable until then.
+- **Notifications disabled.** `NOTIFICATIONS_DISABLED=true` until Open Notificaties
+  (NRC) lands in S-01-c — otherwise ZTC writes 500 trying to notify. Re-enable then.
+- **Zaaktype is a concept**, not published (publishing needs roltypen/statustypen/
+  resultaattypen — beyond the lean seed). List with `?status=alles`.
 - **Image tag.** Currently `openzaak/open-zaak:latest` via `${OPENZAAK_TAG}`; pin to
-  a known-good tag as part of the catalogus-design ADR.
+  a known-good tag (ADR-0002 follow-up).