feat(domain): ProvideDocuments stores the diploma via the ACL then completes the wait (refs #103)

IAclClient.StoreDiplomaAsync + AclHttpClient (base64 JSON to the ACL /documenten
endpoint). ProvideDocuments stores the uploaded bytes against the zaak (when opened)
before completing WachtOpDocumenten; the domain endpoint accepts the file base64-encoded.

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

tests/acceptance/Steps/EenZaakOpenenSteps.cs

@@ -30,6 +30,7 @@ public sealed class EenZaakOpenenSteps
             VerantwoordelijkeOrganisatie = values["verantwoordelijkeOrganisatie"],
             Vertrouwelijkheidaanduiding = values["vertrouwelijkheidaanduiding"],
             ZaaktypeUrl = new Uri(values["zaaktype"]),
+            InformatieobjecttypeUrl = new Uri("http://openzaak/catalogi/api/v1/informatieobjecttypen/dip"),
         };
     }