I need a production-ready mobile app built with Flutter that lets customers browse and purchase physical goods from my store. Core functionality must include: • Robust user authentication so shoppers can register, log in, and manage their profiles. • Seamless payment-gateway integration (Stripe, PayPal, or another mainstream option) to handle secure checkout for credit/debit cards and wallets. • A product-review module where verified buyers can rate and comment on items once an order is complete. The expected flow is straightforward: product catalog → cart → checkout → order confirmation → review. Please structure code for scalability and keep UI components clean so I can extend the catalog later. When you reply, highlight your relevant Flutter e-commerce experience—especially any apps that already use authentication, payments, and review systems. Links or brief case studies are welcome.