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

BACKLOG.md

@@ -199,9 +199,19 @@ _Split from the original S-09 — scoped to the portal only; the approval flow i
 
 ### S-10 · Document upload + boundary timer for document timeout (Flow 2)
 
-**Outcome:** BPMN extended with a "wacht op documenten" user task with a 30-day boundary timer. Self-service portal supports diploma upload. On timeout the case is cancelled.
+Split (issue #11 closed) into two independently-demoable slices per §13 — the original spanned six net-new surfaces including a new ZGW boundary:
 
-**Acceptance:** BDD scenarios for both branches; integration tests for the timer firing.
+#### S-10a · Document-wait task + 30-day timeout cancellation + provision trigger — #102
+
+**Outcome:** BPMN gains a `WachtOpDocumenten` user task with a 30-day (P30D) interrupting boundary timer. On timeout the case is cancelled — the timer runs to a dedicated cancel end-event and the domain aggregate moves to a new terminal status `Verlopen` via an external-worker (mirrors S-14 escalation / S-11 withdrawal). "Documents received" is wired end-to-end (domain endpoint + BFF + a "Documenten aanleveren" button on the self-service page) so the walking-skeleton e2e stays green — but the document is **not yet stored** in ZGW; that is S-10b.
+
+**Acceptance:** BDD both branches (documents-in-time vs timeout-cancel); live timer-fire via the management-API "move" idiom; the registration e2e provides documents before the behandelaar step.
+
+#### S-10b · Real diploma upload stored via the ACL Documenten API — #103
+
+**Outcome:** the self-service "Documenten aanleveren" action becomes a real file upload; the document is stored in the ZGW Documenten (DRC) API and related to the zaak, with all document calls routed through the ACL (§8.1), and the zaak is set to a cancellation status on timeout expiry. Builds on the S-10a trigger/wait. Depends on #102.
+
+**Acceptance:** ACL Documenten gateway integration test; Playwright e2e uploads a real document; the openbaar/zaak reflects the stored document.
 
 ### S-11 · Withdrawal (Flow 3)