feat(F-087): completed feature

project/storefront/src/app/api/cart/route.ts

@@ -0,0 +1,31 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+const API = process.env.NEXT_PUBLIC_API_URL ?? 'http://127.0.0.1:3000';
+
+async function proxy(req: NextRequest, method: 'GET' | 'POST', path: string) {
+  const cookies = req.headers.get('cookie') ?? '';
+  let body: string | undefined;
+  if (method === 'POST') body = await req.text();
+  try {
+    const backendRes = await fetch(`${API}${path}`, {
+      method,
+      headers: {
+        'Content-Type': 'application/json',
+        ...(cookies ? { Cookie: cookies } : {}),
+      },
+      body,
+    });
+    const data = await backendRes.json().catch(() => null);
+    return NextResponse.json(data ?? { error: 'Bad response' }, { status: backendRes.status });
+  } catch {
+    return NextResponse.json({ error: 'Proxy error' }, { status: 502 });
+  }
+}
+
+export async function GET(req: NextRequest) {
+  return proxy(req, 'GET', '/cart');
+}
+
+export async function POST(req: NextRequest) {
+  return proxy(req, 'POST', '/cart/items');
+}