chore: add nextjs template

frontend-nextjs/lib/api.ts

@@ -0,0 +1,22 @@
+export type Product = {
+  id: number;
+  title: string;
+  price_cents: number;
+  image_url: string;
+};
+
+export async function fetchProducts(): Promise<Product[]> {
+  const res = await fetch("/api/products", { cache: "no-store" });
+  if (!res.ok) {
+    throw new Error("Failed to fetch products");
+  }
+  return res.json();
+}
+
+export async function fetchProduct(productId: string): Promise<Product> {
+  const res = await fetch(`/api/products/${productId}`, { cache: "no-store" });
+  if (!res.ok) {
+    throw new Error("Failed to fetch product");
+  }
+  return res.json();
+}