Add spotlight wishlist toggle and shop filter/grid polish

Per-product spotlightShowWishlist opt-in (independent of the global
wishlistEnabled toggle), a reveal-on-hover WishlistButton variant for
multi-card grids (avoids a heart on every card reading as visual noise),
and related PriceRangeFilter/ProductGrid/CustomSelect adjustments.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/lib/__tests__/cartTotals.test.ts

@@ -18,6 +18,7 @@ const product = (overrides: Partial<Product> = {}): Product => ({
   spotlightHeadline: null,
   spotlightText: null,
   spotlightImage: null,
+  spotlightShowWishlist: false,
   variants: [],
   outOfStock: false,
   lowStock: false,