feat(brief): WP-28 demo script, e2e spec, and story gap-fill

Closes phase 6 (Brief v2): a demo script mapping shipped scenarios to
URL+click paths (no Brief v2 PRD ever existed to translate one from —
written directly against the code instead), one e2e spec covering
compose→approve→send and admin republish→drafter-sees-it, and
Storybook state gaps (rejection diff, read-only viewer, org logo,
upload rejection) that prior WPs left uncovered. Flags passage-picker
as dead code, superseded by besluit-panel.

npm run e2e is not verified green in this sandbox — see WP-28's
Deviations section; the pre-existing, unmodified smoke.spec.ts fails
identically here, pointing at a sandbox rendering issue rather than a
regression.

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

docs/README.md

@@ -43,4 +43,5 @@ condensed, cross-linked curriculum.
 | [backlog/README.md](project/backlog/README.md)                                                   | The work-package backlog index (WP-01…WP-48) — the live tracker.               |
 | [prd/0001-mijn-aanvragen-en-wizardstatus.md](project/prd/0001-mijn-aanvragen-en-wizardstatus.md) | PRD — "Mijn aanvragen": running wizards, application status, document preview. |
 | [prd/0002-attribute-based-access-control.md](project/prd/0002-attribute-based-access-control.md) | PRD — attribute-based access control in the UI.                                |
+| [prd/0003-brief-v2-demo-script.md](project/prd/0003-brief-v2-demo-script.md)                     | Demo script — Brief v2 scenarios mapped to a URL + click path (WP-28).         |
 | [SHOWCASE-ROADMAP.md](project/SHOWCASE-ROADMAP.md)                                               | Superseded roadmap (absorbed into `project/backlog/`) — kept for history.      |