fix(infra): let Objecten actually accept the register record (refs #149)

Replaying the gateway's calls against a live Objecten + Objecttypen pair turned
up two blockers CI would only have found after the fact:

- Objecten rejects an objecttype it has not been configured with, and it
  identifies one by uuid — assigned at seed time by a one-shot that runs after
  Objecten's static setup_configuration. Pin the uuid on both sides instead.
- Objecten notifies on every write and notifications_api_common *raises* when
  that config is absent, so every POST 500'd after rolling the object back.
  Objecten → NRC has no broker, worker, kanaal or abonnement yet, so disable
  notifications rather than wire a client that drops every message; S-19b turns
  them on for real.

With both in place the full exchange verifies end to end: lookup → version →
search → create → update (still one object), and a record carrying a bsn is
rejected by the schema. ADR-0028 records both.

infra/docker-compose.yml

@@ -717,6 +717,12 @@ services:
       CACHE_AXES: objecten-redis:6379/0
       DISABLE_2FA: "true"
       OTEL_SDK_DISABLED: "true"
+      # S-19a: Objecten refuses every write while its Notificaties config is absent
+      # (notifications_api_common raises rather than skipping, so POST /objects 500s). Objecten →
+      # NRC is not wired yet — there is no broker, worker, kanaal or abonnement for it — so turn
+      # notifications off rather than fake a delivery path that silently drops every message.
+      # S-19b (#150) sources the projection from Objecten and turns this back on for real.
+      NOTIFICATIONS_DISABLED: "true"
       RUN_SETUP_CONFIG: "true"
     command: /setup_configuration.sh
     # data.yaml is streamed into this external volume by infra/seed-config.sh before start.