feat(saleor): Phase 1 - GraphQL Client Setup

- Add Apollo Client for Saleor GraphQL API
- Create GraphQL fragments (Product, Variant, Checkout)
- Create GraphQL queries (Products, Checkout)
- Create GraphQL mutations (Checkout operations)
- Add TypeScript types for Saleor entities
- Add product helper functions
- Install @apollo/client and graphql dependencies

Part of WordPress/WooCommerce → Saleor migration

src/lib/saleor/products.ts

@@ -0,0 +1,105 @@
+import { saleorClient } from "./client";
+import { GET_PRODUCTS, GET_PRODUCT_BY_SLUG } from "./queries/Products";
+import type { Product, ProductList } from "@/types/saleor";
+
+const CHANNEL = process.env.NEXT_PUBLIC_SALEOR_CHANNEL || "default-channel";
+
+export async function getProducts(
+  locale: string = "SR",
+  first: number = 100
+): Promise<Product[]> {
+  try {
+    const { data } = await saleorClient.query({
+      query: GET_PRODUCTS,
+      variables: {
+        channel: CHANNEL,
+        locale: locale.toUpperCase(),
+        first,
+      },
+    });
+
+    return data?.products?.edges.map((edge: { node: Product }) => edge.node) || [];
+  } catch (error) {
+    console.error("Error fetching products from Saleor:", error);
+    return [];
+  }
+}
+
+export async function getProductBySlug(
+  slug: string,
+  locale: string = "SR"
+): Promise<Product | null> {
+  try {
+    const { data } = await saleorClient.query({
+      query: GET_PRODUCT_BY_SLUG,
+      variables: {
+        slug,
+        channel: CHANNEL,
+        locale: locale.toUpperCase(),
+      },
+    });
+
+    return data?.product || null;
+  } catch (error) {
+    console.error(`Error fetching product ${slug} from Saleor:`, error);
+    return null;
+  }
+}
+
+export function getProductPrice(product: Product): string {
+  const variant = product.variants?.[0];
+  if (!variant?.pricing?.price?.gross?.amount) {
+    return "";
+  }
+  return formatPrice(
+    variant.pricing.price.gross.amount,
+    variant.pricing.price.gross.currency
+  );
+}
+
+export function getProductImage(product: Product): string {
+  if (product.media && product.media.length > 0) {
+    return product.media[0].url;
+  }
+  if (product.variants?.[0]?.media && product.variants[0].media.length > 0) {
+    return product.variants[0].media[0].url;
+  }
+  return "/placeholder-product.jpg";
+}
+
+export function isProductAvailable(product: Product): boolean {
+  const variant = product.variants?.[0];
+  if (!variant) return false;
+  return (variant.quantityAvailable || 0) > 0;
+}
+
+export function formatPrice(amount: number, currency: string = "RSD"): string {
+  return new Intl.NumberFormat("sr-RS", {
+    style: "currency",
+    currency: currency,
+    minimumFractionDigits: 0,
+  }).format(amount);
+}
+
+// Get localized product data
+export function getLocalizedProduct(
+  product: Product,
+  locale: string = "SR"
+): {
+  name: string;
+  slug: string;
+  description: string;
+  seoTitle?: string;
+  seoDescription?: string;
+} {
+  const isEnglish = locale.toLowerCase() === "en";
+  const translation = isEnglish ? product.translation : null;
+
+  return {
+    name: translation?.name || product.name,
+    slug: translation?.slug || product.slug,
+    description: translation?.description || product.description,
+    seoTitle: translation?.seoTitle || product.seoTitle,
+    seoDescription: translation?.seoDescription || product.seoDescription,
+  };
+}