feat(acl,domain): cancel the ZGW zaak on document-timeout expiry (S-10c, closes #106) (#109)

## S-10c · Close the ZGW zaak on document-timeout expiry (closes #106)

Completes the S-10a/S-10b boundary flagged in ADR-0017: when a registration's 30-day document term lapses, the domain now cancels the **ZGW zaak** as well as marking the aggregate `Verlopen`, so OpenZaak and the register no longer diverge.

### What it does
On expiry the `ExpireRegistrationWorker` calls the ACL to set the zaak to a distinct, non-terminal **`Geannuleerd`** status with a **`Vervallen`** resultaat (vs the approval `Afgehandeld` + `Geregistreerd`), resolved **by omschrijving** in the ACL — the ACL-first ordering mirrors approval so a failed ZGW call leaves the job for redelivery rather than diverging the two.

**Path:** Flowable P30D timer → `RegistratieVerlopen` job → domain `ExpireRegistrationWorker` → ACL `POST /annuleringen` → ZGW `resultaten` + `statussen` (Geannuleerd) → aggregate `Verlopen`.

### Layers touched (each red→green)
- **ACL gateway** — `SetZaakToCancellationStatusAsync` (Geannuleerd + Vervallen by name); approval now resolves its `Geregistreerd` resultaat by name too (a second resultaattype now exists).
- **ACL service/API** — `AclService.CancelZaakAsync` + `POST /annuleringen`.
- **Domain** — `IAclClient.CancelZaakAsync` + client; expiry worker cancels the zaak before advancing to `Verlopen`, guarded against redelivery double-cancel.
- **Seed** — non-terminal `Geannuleerd` statustype (volgnummer 2; `Afgehandeld` → 3) + `Vervallen` resultaattype, both idempotent by omschrijving and sharing the zaaktype's procestype.
- **Verify/integration** — ACL↔OpenZaak integration test (live `Geannuleerd` + resultaat); `run-domain-check.sh` fires the real P30D timer and asserts the zaak reaches `Geannuleerd` end-to-end; BDD scenario asserts cancel-on-timeout vs untouched-when-in-time.
- **Docs** — ADR-0019 (cancellation modelling decision), demo-script, BACKLOG.

### Design note (ADR-0019)
ZGW allows only one eindstatus per zaaktype, so `Geannuleerd` is modelled as a **non-terminal** status (it records a cancellation status + resultaat but does not set `einddatum`). This follows the issue's explicit "distinct statustype + resultaat" outcome; the shared-eindstatus alternative is recorded in the ADR.

### Tests
Unit + acceptance all green locally (Acl 38, Big 134, Acceptance 17, Bff 33, EventSubscriber 19). Integration + verify-stack run in CI (need live OpenZaak + selectielijst egress).

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

Reviewed-on: #109

services/acl/Acl.IntegrationTests/OpenZaakFixture.cs

@@ -114,6 +114,19 @@ public sealed class OpenZaakFixture : IDisposable
         return fallback ?? throw new InvalidOperationException($"No statustypen for zaaktype {zaaktypeUrl}");
     }
 
+    /// <summary>Resolve a statustype by its omschrijving (e.g. the S-10c "Geannuleerd" cancellation status).</summary>
+    public async Task<Uri> FindStatustypeByOmschrijvingAsync(Uri zaaktypeUrl, string omschrijving, CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl,
+            "/catalogi/api/v1/statustypen?status=alles&zaaktype=" + Uri.EscapeDataString(zaaktypeUrl.ToString()));
+        var page = await GetJsonAsync(query, ct);
+        foreach (var st in page.GetProperty("results").EnumerateArray())
+            if (st.TryGetProperty("omschrijving", out var o) && o.GetString() == omschrijving)
+                return new Uri(st.GetProperty("url").GetString()!);
+
+        throw new InvalidOperationException($"No '{omschrijving}' statustype for zaaktype {zaaktypeUrl}");
+    }
+
     // A ZGW (vng-api-common) HS256 JWT, mirroring the seed's client. Minted here
     // rather than reusing Acl.Infrastructure's internal minter to keep that internal.
     private string MintToken()