feat(analytics): add OpenPanel tracking to storefront

Add comprehensive OpenPanel analytics tracking:
- Install @openpanel/nextjs SDK
- Add OpenPanelComponent to root layout for automatic page views
- Create useAnalytics hook for tracking custom events
- Track checkout funnel: started, shipping step, order completed
- Track product views and add-to-cart events
- Identify users on order completion
- Add NEXT_PUBLIC_OPENPANEL_CLIENT_ID to environment

src/components/product/ProductDetail.tsx

@@ -20,6 +20,7 @@ import BeforeAfterGallery from "@/components/home/BeforeAfterGallery";
 import HowItWorks from "@/components/home/HowItWorks";
 import NewsletterSection from "@/components/home/NewsletterSection";
 import BundleSelector from "@/components/product/BundleSelector";
+import { useAnalytics } from "@/lib/analytics";
 
 interface ProductDetailProps {
   product: Product;
@@ -99,8 +100,25 @@ export default function ProductDetail({ product, relatedProducts, bundleProducts
   const [urgencyIndex, setUrgencyIndex] = useState(0);
   const [selectedBundleVariantId, setSelectedBundleVariantId] = useState<string | null>(null);
   const { addLine, openCart } = useSaleorCheckoutStore();
+  const { trackProductView, trackAddToCart } = useAnalytics();
   const validLocale = isValidLocale(locale) ? locale : "sr";
 
+  // Track product view on mount
+  useEffect(() => {
+    const localized = getLocalizedProduct(product, locale);
+    const baseVariant = product.variants?.[0];
+    const price = baseVariant?.pricing?.price?.gross?.amount || 0;
+    const currency = baseVariant?.pricing?.price?.gross?.currency || "RSD";
+    
+    trackProductView({
+      id: product.id,
+      name: localized.name,
+      price,
+      currency,
+      category: product.category?.name,
+    });
+  }, [product, locale]);
+
   useEffect(() => {
     const interval = setInterval(() => {
       setUrgencyIndex(prev => (prev + 1) % 3);
@@ -132,6 +150,25 @@ export default function ProductDetail({ product, relatedProducts, bundleProducts
     setIsAdding(true);
     try {
       await addLine(selectedVariantId, 1);
+      
+      // Track add to cart
+      const localized = getLocalizedProduct(product, locale);
+      const baseVariant = product.variants?.[0];
+      const selectedVariant = selectedVariantId === baseVariant?.id 
+        ? baseVariant 
+        : bundleProducts.find(p => p.variants?.[0]?.id === selectedVariantId)?.variants?.[0];
+      const price = selectedVariant?.pricing?.price?.gross?.amount || 0;
+      const currency = selectedVariant?.pricing?.price?.gross?.currency || "RSD";
+      
+      trackAddToCart({
+        id: product.id,
+        name: localized.name,
+        price,
+        currency,
+        quantity: 1,
+        variant: selectedVariant?.name,
+      });
+      
       openCart();
     } finally {
       setIsAdding(false);