fix: set language code before add to cart

Ensure language code is set in checkout store before creating checkout.
This ensures orders created from any page will have correct language.

- Add setLanguageCode to NewHero before addLine
- Add setLanguageCode to ProductDetail before addLine
- Uses current locale from useLocale or props

src/components/home/NewHero.tsx

@@ -15,9 +15,13 @@ interface NewHeroProps {
 
 export default function NewHero({ featuredProduct }: NewHeroProps) {
   const locale = useLocale();
-  const { addLine, openCart } = useSaleorCheckoutStore();
+  const { addLine, openCart, setLanguageCode } = useSaleorCheckoutStore();
 
   const handleAddToCart = async () => {
+    // Set language code before adding to cart
+    if (locale) {
+      setLanguageCode(locale);
+    }
     const variant = featuredProduct?.variants?.[0];
     if (variant?.id) {
       await addLine(variant.id, 1);

src/components/product/ProductDetail.tsx

@@ -99,7 +99,7 @@ export default function ProductDetail({ product, relatedProducts, bundleProducts
   const [isAdding, setIsAdding] = useState(false);
   const [urgencyIndex, setUrgencyIndex] = useState(0);
   const [selectedBundleVariantId, setSelectedBundleVariantId] = useState<string | null>(null);
-  const { addLine, openCart } = useSaleorCheckoutStore();
+  const { addLine, openCart, setLanguageCode } = useSaleorCheckoutStore();
   const { trackProductView, trackAddToCart } = useAnalytics();
   const validLocale = isValidLocale(locale) ? locale : "sr";
 
@@ -147,6 +147,11 @@ export default function ProductDetail({ product, relatedProducts, bundleProducts
   const handleAddToCart = async () => {
     if (!selectedVariantId) return;
 
+    // Set language code before adding to cart
+    if (validLocale) {
+      setLanguageCode(validLocale);
+    }
+
     setIsAdding(true);
     try {
       await addLine(selectedVariantId, 1);