S-18b · Objecten API up in compose, wired to Objecttypen (closes #140) (#143)

## What & why

S-18b, second of the S-18 (#19) split (after S-18a #139/#142). Stands up the upstream Maykin **Objecten API** in the compose stack and wires it to the Objecttypen API — the authoritative object store the ACL will write register records to (S-19).

Closes #140

### What

- **Compose** (main + local): `objecten-db` (**PostGIS** — objects carry geometry), `objecten-redis`, `objecten-init` (RUN_SETUP_CONFIG → migrate + provision token + register the Objecttypen service), `objecten` web (health on `/admin/`, host `:8021`). Verbatim upstream image `maykinmedia/objects-api` pinned to `3.4.0` (nearest release to objecttypes-api `3.4.2`; the two speak over the stable Objecttypes API v2).
- **Seed**: `infra/seed-config.sh objecten` streams `infra/objecten/setup_configuration/data.yaml` into the external `rr-objecten-config` volume — same pattern as S-18a. The data.yaml (1) registers **Objecttypen** as a trusted `zgw_consumers` service (`api_type: orc`, api-key auth with the S-18a dev token) so an object can reference its objecttype, and (2) provisions a dev **static API token** so peers (the ACL, S-19) can write objects.
- **Wiring**: added to `WAIT_SVCS`, `CFG_VOLS`, the `SEED` invocations, `seed-config.sh`, and the CI log-dump. `objecten-init` waits on `objecttypen` being healthy so the service registration is meaningful end to end.
- **Smoke**: `verify-objecten` (`infra/run-objecten-check.sh` + `objecten-check.py`) asserts unauth → 401, token → 200 on `/api/v2/objects`; added as a verify-stack step + a row in the #136 check-summary table.

## Verified locally (end to end, real compose)

Seeded + brought up the real `infra/docker-compose.yml` objecten chain (pulls in objecttypen via `depends_on`): `objecten-init` ran setup_configuration — `token_configuration_success` **and** "Successfully executed step: Configuration to connect with external services" — the web reached healthy, and `make verify-objecten` → **"OK — no-auth 401, token 200"**. Confirmed the registered service via the Objecten django shell:

```
objecttypen | orc | http://objecttypen:8000/api/v2/ | api_key
```

YAML (both compose files + ci.yaml) + shell + python all validated; `docker compose config` clean on both files.

## Definition of Done

- [x] Failing smoke committed first (`test(infra): …`, "no running objecten container"); implementation makes it pass.
- [x] Conventional Commits referencing #140.
- [ ] CI green (verify-stack objecten step).
- [x] `docker compose up` reaches health (objecten healthy on first poll locally).
- [x] Demo note in `docs/demo-script.md`.
- [x] Closed by the merging PR (`closes #140`).

No new ADR: follows the established verbatim-image + seed-config CG-module pattern (S-18a/ADR-0023-era).

🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #143

infra/docker-compose.local.yml

@@ -621,12 +621,76 @@ services:
         condition: service_completed_successfully
     networks: [cg]
 
+  # ── Objecten API (S-18b) — bind-mounted config (local variant) ─────────────
+  objecten-db:
+    image: docker.io/postgis/postgis:17-3.5
+    environment:
+      POSTGRES_USER: objects
+      POSTGRES_PASSWORD: objects
+      POSTGRES_DB: objects
+    volumes:
+      - objecten-db:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U objects"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+    networks: [cg]
+
+  objecten-redis:
+    image: docker.io/library/redis:7
+    networks: [cg]
+
+  objecten-init:
+    image: docker.io/maykinmedia/objects-api:${OBJECTS_TAG:-3.4.0}
+    environment: &objecten-env-local
+      DJANGO_SETTINGS_MODULE: objects.conf.docker
+      SECRET_KEY: ${OBJECTS_SECRET_KEY:-dev-only-not-for-production}
+      DB_HOST: objecten-db
+      DB_NAME: objects
+      DB_USER: objects
+      DB_PASSWORD: objects
+      ALLOWED_HOSTS: "*"
+      CACHE_DEFAULT: objecten-redis:6379/0
+      CACHE_AXES: objecten-redis:6379/0
+      DISABLE_2FA: "true"
+      OTEL_SDK_DISABLED: "true"
+      RUN_SETUP_CONFIG: "true"
+    command: /setup_configuration.sh
+    volumes:
+      - ./objecten/setup_configuration:/app/setup_configuration:ro,z
+    depends_on:
+      objecten-db:
+        condition: service_healthy
+      objecten-redis:
+        condition: service_started
+      objecttypen:
+        condition: service_healthy
+    networks: [cg]
+
+  objecten:
+    image: docker.io/maykinmedia/objects-api:${OBJECTS_TAG:-3.4.0}
+    environment: *objecten-env-local
+    healthcheck:
+      test: ["CMD", "python", "-c", "import requests,sys; sys.exit(0 if requests.head('http://localhost:8000/admin/').status_code in (200,302) else 1)"]
+      interval: 10s
+      timeout: 5s
+      retries: 10
+      start_period: 30s
+    ports:
+      - "8021:8000"
+    depends_on:
+      objecten-init:
+        condition: service_completed_successfully
+    networks: [cg]
+
 volumes:
   oz-db:
   nrc-db:
   flowable-db:
   projection-db:
   objecttypen-db:
+  objecten-db:
   # Carries the seed-generated acl.env (server-assigned zaaktype URLs) from local-seed to the ACL.
   seed-env: