S-19a · ACL writes the RegisterRecord to Objecten on approval (closes #149) (#151)

Closes #149.

**Outcome:** approving a registration now writes the canonical register record to the **Objecten** API as a `RegisterRecord` object, alongside the ZGW eindstatus. OpenZaak holds the process, Objecten holds the register (ADR-0028). The write goes through the ACL (§8.1) and is idempotent on the zaak id, so a replayed approval updates the existing object rather than creating a second one.

S-19 (#20) was split first (CLAUDE.md §13) — it bundled this with re-sourcing the read projection, which is now #150.

### What landed

- `IRegisterRecordGateway` + `RegisterRecord` in `Acl.Application`; `ObjectenGateway` in `Acl.Infrastructure` (static Token auth, CRS headers, objecttype resolved by name to its highest **published** version).
- `AclService.ApproveZaakAsync` writes the record after the eindstatus, keyed on the zaak UUID with the zaak's identificatie as reference.
- Compose wiring for both stacks; `ADR-0028`; demo note; PRD §15 out-of-scope line retired.

### Three things only a live stack found

Running the gateway against a real Objecten + Objecttypen pair while writing this turned up blockers CI would have hit after the fact:

1. **Objecten rejects an objecttype it has not been configured with**, by UUID — assigned at seed time by a one-shot that runs *after* Objecten's static setup_configuration. The UUID is now pinned on both sides.
2. **Objecten 500s on every write when its Notificaties config is absent** (`notifications_api_common` raises rather than skipping). Objecten → NRC has no broker, worker, kanaal or abonnement, so notifications are **disabled** rather than wired to drop every message; #150 turns them on for real.
3. **Objecttypen echoes the request Host into the objecttype `url`**, and Objecten only accepts the one matching its configured `api_root` — so the ACL must read Objecttypen at `http://objecttypen:8000`. This is why the new integration test only passes inside the compose network.

All three are recorded in ADR-0028.

### Verification

- `ObjectenGatewayIntegrationTests` (verify-acl, in-network): two writes for one id leave exactly one object with the second write's status. **Passing locally against live Objecten.**
- The **Playwright happy path** asserts, after the behandelaar approves, that Objecten holds exactly one `RegisterRecord` for *that* reference — missing, duplicated, or non-public-safe all fail.
- ACL mutation score **92.23%** (baseline 91.37%, break 90).
- `make lint` / `make unit` green locally; full-stack `make verify` runs in CI.

## Definition of Done

- [x] A linked Gitea issue exists (#149).
- [x] Failing test written and committed first.
- [x] Implementation makes the test pass.
- [x] Refactor commit follows if structure improved.
- [x] Conventional Commit messages referencing the issue (`refs #149`).
- [x] All Gitea Actions CI jobs green (run 684).
- [x] `docker compose up` from a fresh clone reaches green health checks within 3 minutes (verify-stack step 1).
- [x] Docs touched — ADR-0028, demo note, PRD §15, BACKLOG.
- [x] ADR added: `docs/architecture/adr-0028-objecten-holds-the-register.md`.
- [x] Demo note appended to `docs/demo-script.md`.
- [x] Closed by the merging PR (`closes #149`).

🤖 Generated with [Claude Code](https://claude.com/claude-code)Reviewed-on: #151

services/acl/Acl.Infrastructure/ObjectenOptions.cs

@@ -0,0 +1,20 @@
+namespace Acl.Infrastructure;
+
+/// <summary>
+/// Connection + credential config for the Objecten and Objecttypen APIs. Both authenticate with a
+/// static <c>Authorization: Token …</c> (they are not ZGW JWT APIs), so there is no client-id/secret
+/// pair as with OpenZaak.
+/// </summary>
+public sealed class ObjectenOptions
+{
+    public required Uri BaseUrl { get; init; }
+    public required string Token { get; init; }
+
+    /// <summary>Objecttypen API root — the ACL resolves the objecttype URL + version from it by name
+    /// rather than pinning a seed-time UUID in config (same reasoning as ADR-0021).</summary>
+    public required Uri ObjecttypenBaseUrl { get; init; }
+    public required string ObjecttypenToken { get; init; }
+
+    /// <summary>The objecttype the register record is written as (S-18c registers "RegisterRecord").</summary>
+    public required string ObjecttypeName { get; init; }
+}