test(domain): expiry worker cancels the zaak via the ACL on timeout (refs #106)

S-10c: expiring the aggregate to VERLOPEN is not enough — the ZGW zaak must
also be cancelled through the ACL (§8.1). Adds IAclClient.CancelZaakAsync and
its client/fakes, and asserts the worker cancels a still-open registration's
zaak but leaves an already-resolved one untouched.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

services/domain/Big.Application/Ports.cs

@@ -59,6 +59,12 @@ public interface IAclClient
     /// zaak (§8.1). Returns the stored document's URL.
     /// </summary>
     Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default);
+
+    /// <summary>
+    /// Cancel the zaak on document-timeout expiry (S-10c): the 30-day document term lapsed, so the ACL
+    /// translates this to the ZGW cancellation status/resultaat. The domain never names statustypen.
+    /// </summary>
+    Task CancelZaakAsync(Uri zaakUrl, CancellationToken ct = default);
 }
 
 /// <summary>