feat(infra): Objecten API up in compose, wired to Objecttypen (refs #140)

Stands up the upstream Maykin Objecten API in the stack — own PostGIS DB
+ redis, an -init that runs setup_configuration from the external config
volume (migrate + provision a static token + register the Objecttypen API
as a trusted service), and a health-checked web on host :8021. Objecten's
setup_configuration registers Objecttypen (api_type orc, api_key auth with
the S-18a dev token) so an object can reference its objecttype.

Same verbatim-image + seed-config pattern as S-18a. Wired into WAIT_SVCS,
CFG_VOLS, the SEED invocations, seed-config.sh, and the CI log-dump. Pinned
objects-api 3.4.0 (nearest release to objecttypes-api 3.4.2).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -280,7 +280,7 @@ jobs:
       # Log dump must precede teardown (which removes the containers).
       - name: Dump container logs on failure
         if: failure()
-        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=100 oz-init openzaak nrc-init nrc-web nrc-celery nrc-beat flowable-db flowable-rest flowable-init keycloak acl bff domain projection-db event-subscriber projection-api self-service openbaar behandel beheer objecttypen-db objecttypen-redis objecttypen-init objecttypen tempo prometheus grafana 2>&1 || true
+        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=100 oz-init openzaak nrc-init nrc-web nrc-celery nrc-beat flowable-db flowable-rest flowable-init keycloak acl bff domain projection-db event-subscriber projection-api self-service openbaar behandel beheer objecttypen-db objecttypen-redis objecttypen-init objecttypen objecten-db objecten-redis objecten-init objecten tempo prometheus grafana 2>&1 || true
       - name: Tear down
         if: always()
         run: make down