Money Exchange App & Website

I’m building a full-stack, fully secure money-exchange platform that spans Android, iOS, and a responsive website. The public landing screen must fetch and display up-to-the-second buy/sell rates even for guests, then invite them to sign in.

Authentication will rely on Google Authenticator one-time codes; every sensitive endpoint must be locked behind this 2-factor flow. Once inside, customers need a clean dashboard where they can:
• place buy orders
• place sell orders
• review a complete, filterable transaction history

Behind the scenes I’ll need an admin console that lets me adjust spreads manually or, at the flip of a switch, pull live forex data from an API (feel free to recommend the most cost-effective feed). All price changes should propagate in real time to every client app.

Data security is non-negotiable—please architect encrypted REST/GraphQL endpoints, token-based sessions, and role-based access for staff accounts. Source code must be clean, documented, and ready for future audits.

Deliverables
1. Android and iOS apps (Kotlin/Swift or a robust cross-platform stack) pushed to the respective stores.
2. Dynamic website with the same core features and a mobile-first UI.
3. Admin backend/CMS, database schema, and API layer.
4. Deployment scripts and brief hand-off documentation.

I value maintainability, so using mainstream frameworks (e.g., Flutter + Laravel, React Native + Node, or native stacks) is preferred as long as you can justify the choice. Let me know which architecture you propose, the security standards you follow, and a realistic timeline for an MVP launch.