React Web & Native Productivity App

I’m putting together a unified code-base: a React.js web platform paired with a React Native mobile app whose main purpose is to help users work smarter. The mobile side is firmly a productivity tool, yet I also need two commerce-style capabilities baked in from day one—a browsable product catalog and seamless payment-gateway integration—so users can purchase add-ons or premium content without ever leaving the experience.

Core requirements
• Single sign-on via classic email / password authentication (no social logins needed).
• Fully responsive React.js front-end that shares UI components with the React Native app where practical, keeping styling consistent with React Native Paper or similar.
• Secure payment flow: PCI-compliant handling of card data through a mainstream gateway (Stripe or PayPal are both acceptable—let me know your preference).
• Modular product catalog that I can expand later; initial data can live in JSON or Firestore while we wire up the real back-end.
• Clean, well-commented code, TypeScript preferred, linting in place, and a brief README so another developer can jump in quickly.

Acceptance criteria
1. I can pull the repo, run `npm install && npm run web` or `npm run mobile`, and see both apps locally.
2. Creating an account, signing in, browsing the catalog, and completing a test purchase all work end-to-end.
3. No build warnings, no failing tests, and lighthouse score 90+ on the web build.

If the outline fits your wheelhouse—React 18, React Native 0.73+, Redux Toolkit, secure payment APIs—let’s talk timelines and milestones.