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/docs/atomic-design.mdx

@@ -14,14 +14,42 @@ atoms — that is the whole point: fewer things to understand, nothing bespoke p
 
 <div style={{ display: 'grid', gap: '0.5rem', maxWidth: '32rem', margin: '1.5rem 0' }}>
   {[
-    ['Templates', 'shared/layout', 'shell, page-shell, wizard-shell — the page skeleton', '#1e3a5f'],
-    ['Organisms', 'shared/ui/upload/document-upload …', 'self-contained sections that own a bit of behaviour', '#2a5a8a'],
+    [
+      'Templates',
+      'shared/layout',
+      'shell, page-shell, wizard-shell — the page skeleton',
+      '#1e3a5f',
+    ],
+    [
+      'Organisms',
+      'shared/ui/upload/document-upload …',
+      'self-contained sections that own a bit of behaviour',
+      '#2a5a8a',
+    ],
     ['Molecules', 'shared/ui/form-field, async …', 'a label + control + error, grouped', '#3f7cb5'],
-    ['Atoms', 'shared/ui/button, text-input …', 'thin wrappers over CIBG Huisstijl (Bootstrap) CSS classes', '#6aa6d8'],
+    [
+      'Atoms',
+      'shared/ui/button, text-input …',
+      'thin wrappers over CIBG Huisstijl (Bootstrap) CSS classes',
+      '#6aa6d8',
+    ],
   ].map(([name, where, why, bg], i) => (
-    <div key={name} style={{ background: bg, color: '#fff', padding: '0.75rem 1rem', borderRadius: '6px', marginLeft: `${i * 1.5}rem` }}>
+    <div
+      key={name}
+      style={{
+        background: bg,
+        color: '#fff',
+        padding: '0.75rem 1rem',
+        borderRadius: '6px',
+        marginLeft: `${i * 1.5}rem`,
+      }}
+    >
       <strong>{name}</strong> <span style={{ opacity: 0.85 }}>— {why}</span>
-      <div style={{ fontFamily: 'monospace', fontSize: '0.75rem', opacity: 0.8, marginTop: '0.2rem' }}>{where}</div>
+      <div
+        style={{ fontFamily: 'monospace', fontSize: '0.75rem', opacity: 0.8, marginTop: '0.2rem' }}
+      >
+        {where}
+      </div>
     </div>
   ))}
 </div>