Cross-Platform E-Commerce App

I need a complete mobile shopping experience built simultaneously for iOS and Android. The core of the project is an e-commerce app: product catalogue, cart, checkout, user accounts, and secure payment integration. I am open to Flutter, React Native, or another robust cross-platform framework as long as the final binaries run smoothly on both App Store and Google Play.

Key screens: onboarding / login, browsing and search, product detail with media gallery, cart, checkout with multiple payment gateways, order history, and a lightweight admin portal or API hooks so I can update inventory from my existing system.

Your deliverable should include:
• Source code with clean architecture and clear documentation
• Tested builds, ready for TestFlight and Play Console submission
• A brief hand-off session showing me how to run, build, and push updates

Please factor responsive UI, standard accessibility practices, and at least basic analytics tracking into your estimate. I will supply product data and brand assets; you handle design implementation, development, and initial store submission.