feat(infra): Objecttypen API up in compose with a seeded static token (closes #139) (#142)

## What & why

S-18a, first of the S-18 (#19) split. Stands up the upstream Maykin **Objecttypen API** in the compose stack — the objecttype catalogue the register record (S-18b/S-18c, S-19) will build on.

Closes #139

### What

- **Compose** (main + local): `objecttypen-db` (Postgres), `objecttypen-redis`, `objecttypen-init` (RUN_SETUP_CONFIG → migrate + provision token), `objecttypen` web (health on `/admin/`, host `:8020`). Verbatim upstream image `maykinmedia/objecttypes-api` pinned to `3.4.2`.
- **Seed**: `infra/seed-config.sh objecttypen` streams `infra/objecttypen/setup_configuration/data.yaml` into the external `rr-objecttypen-config` volume — same pattern as OpenZaak/NRC. The data.yaml provisions a dev **static API token** (`tokenauth` setup_configuration step) so peers (Objecten, ACL) can authenticate.
- **Wiring**: added to `WAIT_SVCS`, `CFG_VOLS`, the `SEED` invocations, and the CI log-dump.
- **Smoke**: `verify-objecttypen` (`infra/run-objecttypen-check.sh` + `objecttypen-check.py`) asserts unauth → 401, token → 200; added as a verify-stack step + a row in the #136 check-summary table.

### Split note

#19 was oversized (two CG modules + config + objecttype) → split (§13) into **S-18a** (this), **S-18b** (#140, Objecten wired to Objecttypen), **S-18c** (#141, RegisterRecord objecttype).

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

Seeded + brought up the real `infra/docker-compose.yml` objecttypen chain: `objecttypen-init` ran setup_configuration (`token_configuration_success`), the web reached healthy, and `make verify-objecttypen` → **"OK — no-auth 401, token 200"**. YAML (both compose files + ci.yaml) + shell + python all validated.

## Definition of Done

- [x] Smoke check validates the outcome (live, against the running stack).
- [x] Conventional Commits referencing #139.
- [ ] CI green — see note.
- [x] `docker compose up` reaches health (objecttypen healthy on first poll locally).
- [x] Demo note in `docs/demo-script.md`.

## Note on CI

Additive (a new service + its own smoke step). The fast jobs are unaffected. The **verify-stack** job still can't go green until the pre-existing 1.27/act_runner-2.0.0 bring-up P0 is resolved (fails on plain `main` too) — but the objecttypen bring-up itself is validated locally above. No new ADR: this follows the established verbatim-image + seed-config CG-module pattern (ADR-0023-era).

🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #142

BACKLOG.md

@@ -277,10 +277,16 @@ Split into independently deployable sub-slices (CLAUDE.md §13):
 
 ## Iteration 4 — Objecten and the authoritative register *(milestone: `Iteration 4 — Objecten`)*
 
-### S-18 · Objecten + Objecttypen up in compose; Register objecttype defined
+### S-18 · Objecten + Objecttypen up in compose; Register objecttype defined *(split — #19 closed)*
 
 **Outcome:** Objecten and Objecttypen running. A `RegisterRecord` objecttype defined with the public-safe schema.
 
+Split into independently deployable sub-slices (CLAUDE.md §13):
+
+- **S-18a** (#139) · Objecttypen API up in compose (own DB + seeded config + health + static token).
+- **S-18b** (#140) · Objecten API up in compose, wired to Objecttypen. Depends on S-18a.
+- **S-18c** (#141) · RegisterRecord objecttype defined + registered (public-safe JSON schema). Depends on S-18a/b.
+
 ### S-19 · ACL extension: write register-record to Objecten on approval
 
 **Outcome:** Approval path writes the canonical register record to Objecten, not OpenZaak eigenschappen. Projection now sourced from Objecten events.