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>

src/app/registratie/domain/change-request.machine.ts

@@ -43,7 +43,10 @@ function validate(draft: Draft): Result<Errors, Valid> {
   if (!straat) errors.straat = $localize`:@@validation.straat:Vul straat en huisnummer in.`;
   if (!postcode.ok) errors.postcode = postcode.error;
   if (straat && postcode.ok) {
-    return { ok: true, value: { straat, postcode: postcode.value, woonplaats: draft.woonplaats.trim() } };
+    return {
+      ok: true,
+      value: { straat, postcode: postcode.value, woonplaats: draft.woonplaats.trim() },
+    };
   }
   return { ok: false, error: errors };
 }
@@ -69,7 +72,9 @@ export function reduce(s: State, m: Msg): State {
     case 'Retry':
       return s.tag === 'Failed' ? { tag: 'Submitting', data: s.data } : s;
     case 'SubmitConfirmed':
-      return s.tag === 'Submitting' ? { tag: 'Submitted', data: s.data, referentie: m.referentie } : s;
+      return s.tag === 'Submitting'
+        ? { tag: 'Submitted', data: s.data, referentie: m.referentie }
+        : s;
     case 'SubmitFailed':
       return s.tag === 'Submitting' ? { tag: 'Failed', data: s.data, error: m.error } : s;
     case 'Reset':