test(acl): cancellation gateway posts Geannuleerd + Vervallen; approval picks resultaat by name (refs #106)

S-10c: the document-timeout branch must set the zaak to a distinct
cancellation statustype (Geannuleerd) + resultaat (Vervallen), resolved by
omschrijving. With a second resultaattype present, approval must also
resolve its resultaat (Geregistreerd) by name rather than taking the first.

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

services/acl/Acl.Infrastructure/OpenZaakGateway.cs

@@ -62,6 +62,9 @@ public sealed class OpenZaakGateway(HttpClient http, OpenZaakOptions options) :
             "Setting the zaak status", ct);
     }
 
+    public Task SetZaakToCancellationStatusAsync(Uri zaakUrl, Uri zaaktypeUrl, DateOnly datumStatusGezet, CancellationToken ct = default)
+        => throw new NotImplementedException();
+
     public async Task<string> GetZaakIdentificatieAsync(Uri zaakUrl, CancellationToken ct = default)
     {
         ArgumentNullException.ThrowIfNull(zaakUrl);