docs(portal-self-service): serving/e2e decisions + walking-skeleton demo note (refs #68)

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

docs/demo-script.md

@@ -5,6 +5,28 @@ copy-pasteable walkthrough against a local `make up` stack.
 
 ---
 
+## S-08d — Walking skeleton complete: browser → submit, end-to-end
+
+**Outcome:** the self-service portal is served in the stack and the full front-of-house happy path
+runs in a real browser — **mock DigiD login → submit → confirmation** — closing the walking skeleton
+(portal → BFF → domain → Flowable → ACL → OpenZaak, with the openbaar register reading the projection).
+
+```bash
+# 1. Bring the whole stack up (portal served on :8140, BFF :8080, Keycloak :8180).
+make up
+
+# 2. Automated happy path — Playwright, inside the compose network (issuer-consistent):
+make verify-e2e          # → login as jan-burger → submit → "ontvangen" confirmation
+
+# 3. By hand: open the portal, log in as jan-burger / test123, click "Registratie indienen".
+open http://localhost:8140
+```
+
+> The portal is served same-origin with the BFF (nginx proxies `/self-service` + `/openbaar`), so no
+> CORS; the OIDC authority comes from `/config.json` at runtime. See `docs/frontend-decisions.md`.
+
+---
+
 ## S-08c — Self-service submit form (NL Design System + DigiD)
 
 **Outcome:** a zorgprofessional logs in via mock DigiD and submits a BIG registration through the