feat(admin): merge Site Settings and Wishlist into single Configurações panel

Single-wishlist apps no longer need two separate edit sections.
Both siteTitle/homepageSubtext and wishlist fields now save together
in one action from a unified Configurações card.

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

lib/api.ts

@@ -147,6 +147,8 @@ export interface Item {
   wishlistId: string;
   name: string;
   description: string | null;
+  price: number | null;
+  currency: string;
   quantity: number;
   imageUrl: string | null;
   purchaseUrls: Array<{ label: string; url: string }> | null;