Update Back Link in Order Confirmation Page

- Changed the back link from "/warenkorb" to "/checkout" in the order confirmation page to improve navigation consistency and user experience.

app/pages/order/confirm/[orderId].vue

@@ -184,7 +184,7 @@ onMounted(() => {
 
         <!-- Back Link -->
         <div class="text-center pt-4">
-          <NuxtLink to="/warenkorb" class="text-sm text-experimenta-accent hover:underline">
+          <NuxtLink to="/checkout" class="text-sm text-experimenta-accent hover:underline">
             ← Zurück zum Warenkorb
           </NuxtLink>
         </div>