feat: grid layout, global claim/qty toggles, admin access link, swaddle image

- Public wishlist now renders as responsive 3-col grid instead of list
- Subtitle supports line breaks (whitespace-pre-line)
- claimingEnabled and showQuantity moved to global site settings (not per-item); toggled in admin Configurações panel; claim API enforces server-side
- Admin dashboard shows admin access link with copy button
- Settings API exposes and persists the two new boolean settings

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/header.tsx

@@ -40,7 +40,7 @@ export default function Header({ title, subtitle, imageUrl, actions, maxWidth =
                 {title}
               </h1>
               {subtitle && (
-                <p className={`text-xl sm:text-2xl text-[color:var(--ink-soft)] mb-6 ${imageUrl ? '' : 'max-w-3xl mx-auto'}`}>
+                <p className={`text-xl sm:text-2xl text-[color:var(--ink-soft)] mb-6 whitespace-pre-line ${imageUrl ? '' : 'max-w-3xl mx-auto'}`}>
                   {subtitle}
                 </p>
               )}