feat(shop): show sale badge and strikethrough price on discounted products

Products with compareAtPrice set now show a "-XX%" badge over the
image plus a struck-through original price, wherever price is
displayed (shop grid, homepage spotlight, cart line items). Also
switched the "inkl. MwSt. zzgl. Versand" rows on Pricing.tsx and
ProductSpotlight from items-center to items-baseline — with a large
price next to small disclosure text, center alignment left the
small text visibly floating above the price's bottom edge.

app/todo-cards/components/Pricing.tsx

@@ -55,7 +55,7 @@ export async function Pricing() {
         </div>
 
         <div className="flex flex-col gap-3 items-start w-full lg:w-[18.75rem] lg:shrink-0">
-          <div className="flex gap-2 items-center">
+          <div className="flex gap-2 items-baseline">
             <p className="font-bold text-h3 text-text-primary">{formatPrice(product.price)}</p>
             <p className="text-label text-text-muted">inkl. MwSt. zzgl. Versand</p>
           </div>