feat(acl): diploma upload stored in the ZGW Documenten API (S-10b, closes #103) (#108)

## What & why

S-10b: the self-service **diploma upload** is now real. After submitting, the citizen picks a PDF and
uploads it; the portal base64-encodes it client-side → BFF → domain → **ACL**, which stores it in the
ZGW **Documenten (DRC) API** as an `enkelvoudiginformatieobject` and relates it to the zaak, then the
`WachtOpDocumenten` wait completes and the case advances to beoordeling. Per §8.1 only the ACL talks to
ZGW.

Closes #103

Mechanism in **ADR-0018** (proposal #107). Builds on S-10a (#102). The zaak-close-on-expiry item is
carved to **#106 (S-10c)**.

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation (red→green per layer).
- [x] Conventional Commits referencing the issue (`refs #103`).
- [ ] CI green — all Gitea Actions jobs (pending on this PR).
- [x] `docker compose up` health unaffected (ACL boots on a placeholder informatieobjecttype URL; the real one is injected by verify-domain).
- [x] Docs updated (ADR-0018, demo-script, BACKLOG + S-10c).
- [x] ADR added (`docs/architecture/adr-0018-diploma-upload-via-acl-documenten.md`).
- [x] Demo note in `docs/demo-script.md`.

## Notes for reviewers

- **ACL** (`OpenZaakGateway.StoreDocumentAsync` + `AclService.StoreDiplomaAsync` + `POST /documenten`) reuses the existing gateway patterns (ZGW Bearer, buffered non-chunked body, **no CRS** — Documenten isn't geo). Unit-tested via the stub handler; an **integration test** stores a real document against live OpenZaak (verify-acl).
- **Transport:** base64 JSON on every hop (portal encodes client-side) — I deviated from proposal #107's multipart to keep one contract shape and avoid `IFormFile`/antiforgery/multipart-client plumbing; fine at diploma size (ADR-0018 §Alternatives).
- **Infra:** `seed_catalogus.py` seeds + publishes a "Diploma" `informatieobjecttype` and relates it to the zaaktype (while both concept); `verify-domain` injects its URL into the ACL. No new ZGW scopes (seed applicatie has `heeft_alle_autorisaties`).
- **e2e:** uploads a real PDF (`setInputFiles`) after the openbaar INGEDIEND row confirms the zaak is open (so storage doesn't race the OpenZaak worker).
- **Scope boundary:** the ZGW zaak is not set to a cancellation status on 30-day expiry — that's #106 (S-10c).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #108

services/domain/Big.Tests/Fakes.cs

@@ -110,4 +110,13 @@ internal sealed class FakeAclClient(Uri? zaakUrl = null) : IAclClient
         ApprovedZaakUrl = zaakUrl;
         return Task.CompletedTask;
     }
+
+    public (Uri ZaakUrl, byte[] Content, string FileName, string ContentType)? StoredDiploma { get; private set; }
+    public static readonly Uri DefaultDocumentUrl = new("http://openzaak/documenten/api/v1/enkelvoudiginformatieobjecten/doc");
+
+    public Task<Uri> StoreDiplomaAsync(Uri zaakUrl, byte[] content, string fileName, string contentType, CancellationToken ct = default)
+    {
+        StoredDiploma = (zaakUrl, content, fileName, contentType);
+        return Task.FromResult(DefaultDocumentUrl);
+    }
 }

services/domain/Big.Tests/ProvideDocumentsTests.cs

@@ -3,52 +3,60 @@ using Big.Domain;
 
 namespace Big.Tests;
 
-// S-10a (#102): the "documents received" use case. A zorgprofessional supplies the documents their
-// registration is waiting for; the handler completes the WachtOpDocumenten task via the Workflow Client
-// so the process leaves the 30-day wait and continues to beoordeling. Owner-scoped by the caller's bsn,
-// like WithdrawRegistration. (The real file upload + ZGW storage is S-10b; this is the trigger path.)
+// S-10a/S-10b (#102/#103): the "documents received" use case. A zorgprofessional supplies the diploma
+// their registration is waiting for; the handler stores it in ZGW via the ACL and completes the
+// WachtOpDocumenten task via the Workflow Client so the process continues to beoordeling. Owner-scoped
+// by the caller's bsn, like WithdrawRegistration.
 public class ProvideDocumentsTests
 {
     private const string Bsn = "123456782";
+    private static readonly Uri Zaak = new("http://openzaak/zaken/api/v1/zaken/abc");
 
     private static Registration Submitted(string processInstanceId = "proc-1")
     {
         var registration = Registration.Submit(Bsn);
         registration.RecordProcessStarted(processInstanceId);
+        registration.AttachZaak(Zaak);
         return registration;
     }
 
-    private static ProvideDocumentsCommand Command(RegistrationId id, string bsn = Bsn) => new(id, bsn);
+    private static ProvideDocumentsCommand Command(RegistrationId id, string bsn = Bsn) =>
+        new(id, bsn, [1, 2, 3], "diploma.pdf", "application/pdf");
 
     [Fact]
-    public async Task Providing_documents_completes_the_document_wait()
+    public async Task Providing_documents_stores_the_diploma_and_completes_the_wait()
     {
         var store = new FakeRegistrationStore();
         var registration = Submitted("proc-42");
         store.Seed(registration);
         var workflow = new FakeWorkflowClient();
-        var handler = new ProvideDocuments(store, workflow);
+        var acl = new FakeAclClient();
+        var handler = new ProvideDocuments(store, workflow, acl);
 
         var outcome = await handler.HandleAsync(Command(registration.Id));
 
         Assert.Equal(ProvideDocumentsOutcome.Accepted, outcome);
+        // Stored against the registration's zaak, carrying the uploaded bytes + file metadata.
+        Assert.Equal((Zaak, new byte[] { 1, 2, 3 }, "diploma.pdf", "application/pdf"), acl.StoredDiploma);
+        // …and the wait is completed so beoordeling can proceed.
         Assert.Equal("proc-42", workflow.CompletedDocumentWaitFor);
     }
 
     [Fact]
     public async Task A_different_bsn_cannot_provide_documents()
     {
-        // Owner-scoping: only the registration's own bsn may supply its documents. Another bsn is told
-        // NotFound (existence not revealed) and the wait is not completed.
+        // Owner-scoping: another bsn is told NotFound; nothing is stored or completed.
         var store = new FakeRegistrationStore();
         var registration = Submitted();
         store.Seed(registration);
         var workflow = new FakeWorkflowClient();
-        var handler = new ProvideDocuments(store, workflow);
+        var acl = new FakeAclClient();
+        var handler = new ProvideDocuments(store, workflow, acl);
 
         var outcome = await handler.HandleAsync(Command(registration.Id, bsn: "999999990"));
 
         Assert.Equal(ProvideDocumentsOutcome.NotFound, outcome);
+        Assert.Null(acl.StoredDiploma);
         Assert.Null(workflow.CompletedDocumentWaitFor);
     }
 
@@ -56,30 +64,33 @@ public class ProvideDocumentsTests
     public async Task Providing_for_an_unknown_registration_is_not_found()
     {
         var store = new FakeRegistrationStore();
-        var handler = new ProvideDocuments(store, new FakeWorkflowClient());
+        var handler = new ProvideDocuments(store, new FakeWorkflowClient(), new FakeAclClient());
 
         Assert.Equal(ProvideDocumentsOutcome.NotFound, await handler.HandleAsync(Command(RegistrationId.New())));
     }
 
     [Fact]
-    public async Task Providing_before_a_process_started_is_accepted_without_calling_the_workflow()
+    public async Task Providing_before_a_zaak_is_opened_does_not_store_but_still_completes_the_wait()
     {
-        // No process yet → no wait task to complete; the request still stands (best-effort, mirroring
-        // WithdrawRegistration) and the Workflow Client is not called.
+        // No zaak yet → nothing to file the document against, but the request still stands (best-effort,
+        // mirroring WithdrawRegistration). The wait is completed if a process is running.
         var store = new FakeRegistrationStore();
-        var registration = Registration.Submit(Bsn); // no RecordProcessStarted
+        var registration = Registration.Submit(Bsn);
+        registration.RecordProcessStarted("proc-9"); // process started, but no zaak attached
         store.Seed(registration);
         var workflow = new FakeWorkflowClient();
-        var handler = new ProvideDocuments(store, workflow);
+        var acl = new FakeAclClient();
+        var handler = new ProvideDocuments(store, workflow, acl);
 
         var outcome = await handler.HandleAsync(Command(registration.Id));
 
         Assert.Equal(ProvideDocumentsOutcome.Accepted, outcome);
-        Assert.Null(workflow.CompletedDocumentWaitFor);
+        Assert.Null(acl.StoredDiploma);
+        Assert.Equal("proc-9", workflow.CompletedDocumentWaitFor);
     }
 
     [Fact]
     public async Task Rejects_a_null_command()
         => await Assert.ThrowsAsync<ArgumentNullException>(() =>
-            new ProvideDocuments(new FakeRegistrationStore(), new FakeWorkflowClient()).HandleAsync(null!));
+            new ProvideDocuments(new FakeRegistrationStore(), new FakeWorkflowClient(), new FakeAclClient()).HandleAsync(null!));
 }