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/seed-config.sh

@@ -13,7 +13,7 @@
 # subcommand. Fixed-name `external` volumes keep the names deterministic across
 # both runtimes. See docs/runbooks/gitea-actions-gotchas.md.
 #
-# Usage: seed-config.sh <key> [<key> ...]   where key ∈ { oz, kc, fl }
+# Usage: seed-config.sh <key> [<key> ...]   where key ∈ { oz, nrc, kc, fl, objecttypen, objecten }
 set -euo pipefail
 
 here="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -33,7 +33,7 @@ populate() {  # volume  source(file or dir/.)
   echo "  seeded $vol"
 }
 
-[ "$#" -gt 0 ] || { echo "usage: seed-config.sh <oz|nrc|kc|fl|objecttypen> ..." >&2; exit 2; }
+[ "$#" -gt 0 ] || { echo "usage: seed-config.sh <oz|nrc|kc|fl|objecttypen|objecten> ..." >&2; exit 2; }
 
 # The registratie process (BPMN) and its diploma-eligibility DMN are deployed as SEPARATE Flowable
 # deployments — the process engine and the DMN engine each own theirs (S-13, ADR-0016). flowable-rest
@@ -50,6 +50,7 @@ for key in "$@"; do
     nrc) populate rr-nrc-config "$here/opennotificaties/setup_configuration/." ;;
     kc) populate rr-kc-realms "$here/keycloak/realms/." ;;
     objecttypen) populate rr-objecttypen-config "$here/objecttypen/setup_configuration/." ;;
+    objecten) populate rr-objecten-config "$here/objecten/setup_configuration/." ;;
     fl) d="$(mktemp -d)"; stage_flowable_workflows "$d"; populate rr-fl-bpmn "$d/." ;;
     *)  echo "unknown seed key: $key" >&2; exit 2 ;;
   esac