test(workflow): diploma routing — acceptance + live foreign→CBGV path (S-13, refs #14)

Gherkin scenarios assert the submit carries the diploma origin (domestic/foreign)
into the process. verify-domain now submits a foreign registration and asserts it
parks at CBGVAdvies before Beoordelen, completes CBGV, then advances to Beoordelen
— exercising both DMN branches through the engine (the domestic DIRECT path is the
first registration already parking straight at Beoordelen).

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

tests/acceptance/Steps/EenDiplomaRouterenSteps.cs

@@ -0,0 +1,36 @@
+using Acceptance.Support;
+using Big.Application;
+using Big.Domain;
+using Reqnroll;
+using Xunit;
+
+namespace Acceptance.Steps;
+
+/// <summary>Bindings for <c>EenDiplomaRouteren.feature</c> (S-13). Drives the submit use case against
+/// in-memory ports and asserts the registratie process is started carrying the diploma origin — the
+/// domain's contribution to flow 4. The DMN evaluation and the foreign→CBGV-advies routing it drives
+/// are verified live (verify-domain); one instance per scenario.</summary>
+[Binding]
+[Scope(Feature = "Een diploma op herkomst routeren")]
+public sealed class EenDiplomaRouterenSteps
+{
+    private readonly InMemoryRegistrationStore _store = new();
+    private readonly InMemoryWorkflowClient _workflow = new();
+    private DiplomaOrigin _origin;
+
+    [Given("a zorgprofessional with a \"(.*)\" diploma")]
+    public void GivenAZorgprofessionalWithADiploma(string origin)
+        => _origin = Enum.Parse<DiplomaOrigin>(origin, ignoreCase: true);
+
+    [When("they submit their registration")]
+    public async Task WhenTheySubmitTheirRegistration()
+        => await new SubmitRegistration(_store, _workflow).HandleAsync(
+            new SubmitRegistrationCommand("123456782", _origin));
+
+    [Then("the registratie process is started carrying a \"(.*)\" diploma")]
+    public void ThenTheProcessIsStartedCarryingTheDiploma(string expected)
+    {
+        Assert.NotNull(_workflow.StartedFor);
+        Assert.Equal(Enum.Parse<DiplomaOrigin>(expected, ignoreCase: true), _workflow.StartedWithOrigin);
+    }
+}