feat(workflow): document-wait task + 30-day timeout cancellation (S-10a, closes #102) (#105)

## What & why

S-10a, the **workflow/timeout spine** of the (split) document-upload slice: the registratie process
now parks at a **`WachtOpDocumenten`** user task with an **interrupting `P30D` boundary timer**. When
the documents arrive the task completes and the process continues into the diploma routing (S-13) →
Beoordelen; if the 30 days lapse, the timer cancels the wait, runs a `RegistratieVerlopen`
external-worker task, and the domain expires the aggregate to a new terminal status **`Verlopen`**.
Backend only — the real upload trigger (portal → BFF → ACL → Documenten API) is S-10b (#103).

Closes #102

Mechanism recorded in **ADR-0017**; opened as proposal #104. Mirrors the S-14 escalation
(boundary-timer + external-worker) and S-11 withdrawal (interrupting cancel) patterns.

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation (red→green pairs per layer).
- [x] Implementation makes the test pass.
- [x] Conventional Commits referencing the issue (`refs #102`).
- [ ] CI green — all Gitea Actions jobs (pending on this PR).
- [x] `docker compose up` health unaffected (no new services; deploy path unchanged).
- [x] Docs updated (ADR-0017, demo-script, BACKLOG split).
- [x] ADR added (`docs/architecture/adr-0017-document-wait-timeout-cancellation.md`).
- [x] Demo note in `docs/demo-script.md`.

## Notes for reviewers

- **Domain** (`Registration.Expire()` + `Verlopen`), **application** (`ExpireRegistrationWorker`),
  **infra** (`RegistratieVerlopenProcessor`/`Pump`, `IRegistratieVerlopenClient`, Flowable
  acquire/complete + `CompleteDocumentWaitAsync`) — the timeout counterpart to the OpenZaak/escalation
  worker trios; idempotent per §8.6.
- **BPMN** verified live against a `flowable-rest` probe: complete `WachtOpDocumenten` → routes to
  Beoordelen; fire the P30D timer → `RegistratieVerlopen` job (carrying `registrationId`) + the wait
  task cancelled. `verify-domain` exercises both branches in-stack (completes the wait in every existing
  block; fires the timer and asserts `Verlopen` in a new block).
- **Scope boundary:** on expiry the aggregate goes `Verlopen` and the process ends, but the ZGW *zaak*
  is not yet set to a cancellation status — that needs a new ACL method + statustype seeding and is
  folded into S-10b (noted in ADR-0017).
- `CompleteDocumentWaitAsync` is built and HTTP-tested here but not yet called from a domain endpoint;
  S-10b wires the upload trigger to it.

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

Reviewed-on: #105

apps/self-service/src/app/registration/registration-page.spec.ts

@@ -20,10 +20,12 @@ class FakeAuth extends AuthService {
 function providers(
   post = vi.fn().mockReturnValue(of({ registrationId: 'reg-9', status: 'Ingediend' })),
   withdraw = vi.fn().mockReturnValue(of(undefined)),
+  provideDocuments = vi.fn().mockReturnValue(of(undefined)),
 ) {
   return {
     post,
     withdraw,
+    provideDocuments,
     providers: [
       { provide: AuthService, useClass: FakeAuth },
       {
@@ -31,6 +33,7 @@ function providers(
         useValue: {
           postSelfServiceRegistrations: post,
           postSelfServiceRegistrationsIdWithdraw: withdraw,
+          postSelfServiceRegistrationsIdDocuments: provideDocuments,
         },
       },
     ],
@@ -80,6 +83,37 @@ describe('RegistrationPage', () => {
     expect(await screen.findByText(/ingetrokken/i)).toBeTruthy();
   });
 
+  it('offers to provide documents after submitting, and doing so confirms', async () => {
+    const { provideDocuments, providers: p } = providers();
+    await render(RegistrationPage, { providers: p });
+
+    fireEvent.click(screen.getByRole('button', { name: /indienen/i }));
+    await screen.findByText(/ontvangen/i);
+
+    fireEvent.click(await screen.findByRole('button', { name: /documenten aanleveren/i }));
+
+    // The provide-documents call is keyed by the reference the submit returned, and the page confirms.
+    expect(provideDocuments).toHaveBeenCalledWith('reg-9');
+    expect(await screen.findByText(/documenten.*aangeleverd/i)).toBeTruthy();
+  });
+
+  it('surfaces a provide-documents failure and keeps the action available', async () => {
+    const { providers: p } = providers(
+      vi.fn().mockReturnValue(of({ registrationId: 'reg-9', status: 'Ingediend' })),
+      vi.fn().mockReturnValue(of(undefined)),
+      vi.fn().mockReturnValue(throwError(() => new Error('documents rejected'))),
+    );
+    await render(RegistrationPage, { providers: p });
+
+    fireEvent.click(screen.getByRole('button', { name: /indienen/i }));
+    await screen.findByText(/ontvangen/i);
+    fireEvent.click(await screen.findByRole('button', { name: /documenten aanleveren/i }));
+
+    expect(await screen.findByRole('alert')).toBeTruthy();
+    expect(screen.queryByText(/aangeleverd/i)).toBeNull();
+    expect(screen.getByRole('button', { name: /documenten aanleveren/i })).toBeTruthy();
+  });
+
   it('surfaces a withdraw failure and keeps the action available', async () => {
     const { providers: p } = providers(
       vi.fn().mockReturnValue(of({ registrationId: 'reg-9', status: 'Ingediend' })),