docs: archive the finished backlogs (RD-30)

Two backlog trees are complete: `docs/project/backlog/` (75 files, every
WP done) and `docs/project/refactor-backlog-setup/` (the arc before it).
Move both under `docs/project/archive/` with `git mv`, so history stays
intact through `git log --follow`. `SHOWCASE-ROADMAP.md` moves with them,
because it points at the now-archived backlog README.

Add `docs/project/archive/README.md`. It states that these trees are
historical and names the two directories that are still live.

Repoint every inbound reference named in RD-30's Files table: CLAUDE.md,
the root README, both backend READMEs, `LetterHtml.cs`, `a11y.mdx`, the
`document-feature` and `new-ssp` skills, and the readable-codebase PLAN,
README, and RD-19 ticket. Fix two upward-relative links inside the moved
WP files (WP-68, WP-69) that gained a directory level and would otherwise
break. Repoint `.prettierignore`'s two agent-prompt exclusions to their
new path, so prettier keeps leaving those files' exact wording alone.

Mark RD-30 done and check off its acceptance criteria; flip its README
row to done.

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

docs/project/archive/backlog/WP-36-admin-cases.md

@@ -0,0 +1,49 @@
+# WP-36 — Admin cases page + admin delete
+
+Status: done
+Phase: 7 — refinements
+
+## Why
+
+Admins can maintain stamdata and org-templates but have no view of the cases (aanvragen) in the
+register, and no way to remove an erroneous one. This WP adds an admin-only overview of **all**
+cases across owners and an admin **delete** that can remove any case — the back-office counterpart
+of the user's own dashboard.
+
+## Decisions (made while building — no spec existed; flagged for review)
+
+- **Single capability `cases:manage`** covers both the list and the delete (one back-office
+  concern), following the `orgtemplate:edit` / `stamdata:edit` precedent exactly (Authz role→cap +
+  a `CanManageCases` gate + a `CasesAdmin(ctx,…)` helper; FE `Capability` union + `me.adapter`
+  `KNOWN` + `capabilityGuard` + nav item + `role.interceptor` prefix).
+- **Page lives in `registratie` (not `beheer`).** `registratie` owns the `Aanvraag` aggregate, so
+  the admin view reuses its `aanvraag-view` labels + `parseApplications` trust boundary instead of
+  duplicating them — and it respects the layer boundary (`beheer` may not import `registratie`).
+  This matches the existing pattern (stamdata-admin lives in `beheer` because `beheer` owns
+  stamdata; org-template-admin in `brief`). Routed at `/beheer/zaken` for a legible admin URL.
+- **Admin delete removes ANY case** — any owner, submitted or not — unlike the user-facing
+  `DELETE /applications/{id}` (owner-scoped, 409 on a submitted case). That is the admin power.
+- **Native `confirm()` guards the delete.** No confirm-dialog component exists (the only precedent
+  is a native `confirm()` in behandel-scherm); the delete is irreversible, so it gets a prompt
+  rather than the dashboard's no-confirm optimistic cancel.
+- **Single owner in practice.** Only `DemoOwner` exists, so the list shows that owner's cases with
+  an Owner column; no fake multi-user seed was added (the endpoint is cross-owner-capable —
+  `ListAll()` — so real multi-owner data would just appear).
+
+## Files
+
+- Backend: `ApplicationStore.ListAll()` + `DeleteAny(id)`; `ApplicationSummaryDto.Owner` +
+  `ToAdminSummaryDto`; `Authz` cap + `CanManageCases`; `Program.cs` `CasesAdmin` gate + `GET
+/admin/cases` + `DELETE /admin/cases/{id}`; `AdminCasesTests` (+ update the org-template `/me`
+  cap-list assertion). SQLite can't `ORDER BY DateTimeOffset` → `ListAll` sorts client-side.
+- FE: `capability.ts` + `me.adapter` `KNOWN` + `role.interceptor` (`/api/v1/admin/cases`);
+  `aanvraag.ts` `owner?`; `applications.adapter` `listAll`/`deleteAny` + parse owner;
+  `registratie/application/admin-cases.store.ts` (+spec); `registratie/ui/admin-cases.page.ts`;
+  route in `app.routes.ts`; nav item in `site-header`; new `$localize` ids + English targets.
+
+## Acceptance criteria
+
+- [x] Admin-only page at `/beheer/zaken` lists all cases (owner + type + status), gated by
+      `cases:manage` (denial alert for non-admins; server re-enforces via `CasesAdmin`).
+- [x] Admin delete removes any case (incl. submitted); confirmed, optimistic with rollback.
+- [x] `npm run ci` green (336 FE tests, backend 129, localized build, drift clean after commit).