feat(fp): WP-19 — Playwright e2e smoke against the real FE+backend

Adds a happy-path spec (login → dashboard → registratie wizard, including
a real identity-document upload → real submit) and a degraded-path spec
(?scenario=error → <app-async> error slot → retry), both driving the real
app against the real .NET backend, plus a CI job that boots both.

Writing the retry spec surfaced a real bug: AsyncComponent's retry() only
reloads a [resource]-fed instance, so every real page (all [data]-fed via
a store's RemoteData) had a silently no-op retry button. Added a
retryClicked output and wired it on the dashboard's two async blocks.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -31,6 +31,7 @@ cd backend && dotnet run --project src/BigRegister.Api   # API → http://localh
 
 npm run storybook    # component library, organized by atomic layer
 npm run gen:api      # regenerate the typed API client from the backend OpenAPI doc
+npm run e2e          # Playwright smoke tests against the running app + backend (both must be up)
 ```
 
 Flow: **Login → Dashboard → Mijn gegevens (wijziging) → Herregistratie → Intake**.