style: format frontend, docs and skills with prettier; add .prettierignore

One-time prettier --write so the new format:check CI gate starts green.
.prettierignore excludes generated (api-client.ts, documentation.json),
vendored (public/cibg-huisstijl), and backend (dotnet format owns it).

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

docs/backlog/WP-05-parse-boundaries.md

@@ -30,7 +30,7 @@ principle (every response through a hand-written `parse*` returning `Result`).
 - `src/app/registratie/infrastructure/big-register.adapter.ts` (~line 25) —
   `n.type as AantekeningType` → validated parse
 - `src/app/brief/infrastructure/brief.adapter.ts` (~line 189) — `dto.scope as
-  PassageScope` → validated parse (the file is otherwise parse-heavy; this one field skips)
+PassageScope` → validated parse (the file is otherwise parse-heavy; this one field skips)
 - New co-located specs: `intake-policy.adapter.spec.ts`, extend
   `big-register.adapter.spec.ts` / `brief.adapter.spec.ts` (create if missing)
 - New `src/docs/parse-dont-validate.mdx` — title `Foundations/Parse, don't validate`
@@ -57,7 +57,7 @@ GREEN + `npm run test-storybook:ci`. Smoke: intake wizard still loads its policy
 
 ## Out of scope
 
-Runtime validation on *every* endpoint (explicitly out of scope for the POC per
+Runtime validation on _every_ endpoint (explicitly out of scope for the POC per
 CLAUDE.md); `digid.adapter.ts` (faked auth, sanctioned).
 
 ## Risks