S-26/#162 · Werkbak refreshes itself when a registration is ready for beoordeling (#164)

## What & why

The behandel werkbak now **refreshes itself** while it is open, so a registration that reaches
beoordeling after the behandelaar opened the page shows up on its own — no reload.

`interval(WERKBAK_REFRESH_MS)` (5 s) re-reads the existing BFF endpoint, scoped to the page with
`takeUntilDestroyed()`. A *background* read leaves the rows and states on screen alone until it has
an answer, so a tick never flashes the loading state over rows being read and one failed poll never
swaps the list for the error alert; a read that comes back also clears an earlier failure, so the
view recovers on its own rather than needing the very reload this slice removes.

No new endpoint, dependency or server-side state, and no service boundary moves — rxjs and
`GET /behandel/werkbak` are both already here. **ADR-0032** records why polling rather than a pushed
stream: nothing notifies the BFF either, so SSE/WebSockets would poll the domain *inside* the BFF for
the same freshness, plus connection lifecycle, nginx buffering and a stateful BFF. Proposal: #163.

Closes #162

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation.
- [x] Implementation makes the test pass; refactor commit if structure improved.
- [x] Conventional Commits referencing the issue (`refs #162`).
- [ ] CI green — all Gitea Actions jobs.
- [x] `docker compose up` from a fresh clone reaches green health checks within 3 minutes (unchanged; only the behandel bundle differs).
- [x] Docs updated if behaviour, contracts, or operations changed.
- [x] ADR added in `docs/architecture/` (ADR-0032).
- [x] Demo note in `docs/demo-script.md` (user-visible).

## Notes for reviewers

**The e2e is the real acceptance test, and it took two goes to make it one.** Simply dropping the
`staff.reload()` from the happy path proved nothing: the werkbak was visited *after* the documents
were supplied, so the row was already there at page load. The spec now logs the behandelaar in
**first**, asserts the row is not there yet, and only then has the citizen supply the documents that
route it to Beoordelen — so the row can only reach that already-open, never-reloaded page via the
refresh. Verified both ways against a live stack: with the interval stubbed out it fails at
`Goedkeuren <ref> … element(s) not found` after 30 s; with it, the behandel nginx logs the poll that
delivers the row. The page is foregrounded before the assertion because Chromium throttles timers in
a hidden tab.

**Ceiling (named in the ADR):** a fixed 5 s interval, per open page, that keeps polling in a
background tab; each tick costs one Flowable task query plus a store read per open task. Upgrade
path: publish task events from the domain, then swap the `interval` for a stream — the endpoint
contract and the rendering stay put. Gate on `document.visibilityState` first if request volume is
the concern.

**Two housekeeping notes, neither blocking:**
- #162 is on **no milestone** (DoD item 1). It is portal UX, so it fits neither *Data Governance*
  nor *Production Posture* cleanly — your call where it lands.
- The issue titles itself **S-26**, which already belongs to the self-service resume slice (#111,
  `BACKLOG.md`). Everything here references **#162**; worth renumbering the title if the S-ids are
  meant to stay unique. `BACKLOG.md` is untouched for the same reason (it mirrors the active
  milestone, and this slice is on none).Reviewed-on: #164

docs/demo-script.md

@@ -5,6 +5,40 @@ copy-pasteable walkthrough against a local `make up` stack.
 
 ---
 
+## S-26/#162 — the werkbak refreshes itself (ADR-0032)
+
+**Outcome:** a registration that reaches beoordeling while a behandelaar already has the werkbak open
+**appears on its own** — no reload. The page re-reads `GET /behandel/werkbak` every 5 seconds; a
+background refresh swaps the rows in without flashing the loading state, and a transient failure no
+longer strands the view on its error message until someone reloads.
+
+```bash
+# 1. Two windows. Left: the behandel werkbak, already open and idle.
+python3 infra/keycloak/check_realms.py otp   # a code, valid right now
+open http://localhost:8142                   # merel-behandelaar / test123 + that code
+#
+# 2. Right: submit a registration and supply its documents (this is what routes it to Beoordelen).
+open http://localhost:8140                   # jan-burger / test123 → indienen → upload a PDF
+#
+# 3. Watch the left window. Within ~5 seconds the new reference appears in the werkbak — the page was
+#    never reloaded and never left the werkbak.
+#
+# 4. Automated, end to end: the happy path now waits for the werkbak row WITHOUT reloading, so the
+#    absence of the reload IS the assertion.
+make verify-e2e        # → registration.spec: "… → behandelaar goedkeurt → public INGESCHREVEN"
+#
+# 5. Component level (background refresh, failure recovery, teardown):
+pnpm nx test behandel  # → "picks up a newly submitted registration without a reload" (+3 guards)
+```
+
+**The path:** unchanged — portal → BFF `GET /behandel/werkbak` → domain `Werkbak` → Flowable. Only the
+page's cadence is new: `interval(WERKBAK_REFRESH_MS)` scoped to the page with `takeUntilDestroyed()`.
+
+**Not push:** nothing notifies the BFF either, so SSE/WebSockets would poll the domain inside the BFF
+for the same freshness plus connection state — see ADR-0032 for the trade-off and the upgrade path.
+
+---
+
 ## S-19a — approval writes the register record to Objecten (#149, ADR-0028)
 
 **Outcome:** approving a registration no longer only moves the ZGW zaak to its eindstatus — it also