test(acl,e2e): live diploma-upload coverage (refs #103)

- ACL integration test: stores a real document against a published Diploma
  informatieobjecttype and asserts it is persisted (bestandsnaam, informatieobjecttype,
  bestandsomvang) and related to the zaak.
- e2e: the registration journey now selects a PDF and uploads it (setInputFiles)
  before the behandelaar step.

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

services/acl/Acl.IntegrationTests/OpenZaakFixture.cs

@@ -77,6 +77,18 @@ public sealed class OpenZaakFixture : IDisposable
         return JsonDocument.Parse(json).RootElement.Clone();
     }
 
+    /// <summary>The URL of the published "Diploma" informatieobjecttype (S-10b), or null when the
+    /// stack has not been seeded with OZ_PUBLISH=1. `status=definitief` returns published types only.</summary>
+    public async Task<Uri?> FindPublishedDiplomaInformatieobjecttypeAsync(CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl, "/catalogi/api/v1/informatieobjecttypen?status=definitief");
+        var page = await GetJsonAsync(query, ct);
+        foreach (var iot in page.GetProperty("results").EnumerateArray())
+            if (iot.TryGetProperty("omschrijving", out var o) && o.GetString() == "Diploma")
+                return new Uri(iot.GetProperty("url").GetString()!);
+        return null;
+    }
+
     /// <summary>The zaaktype's eindstatus (terminal statustype) URL — the one an approval sets.</summary>
     public async Task<Uri> FindEindstatustypeAsync(Uri zaaktypeUrl, CancellationToken ct = default)
     {