Paystack Integration for Web+App work should take strictly 5 hours

I need an experienced senior full-stack developer to connect Paystack to both my website and its companion Android app. The web platform runs a mixed PHP and Node.js backend, while the mobile side is built in React Native, so proven competence with all three stacks is essential.

The task covers:
• Adding Paystack’s secure checkout flow to the site and app UI.
• Writing the server-side hooks in PHP/Node.js for charge creation, callbacks, and webhook verification.
• Ensuring transactions appear correctly in the Paystack dashboard and that successful, failed, and cancelled states propagate back to my own order logic.
• Implementing tokenised/recurring capability and refund endpoints only if Paystack’s standard SDK methods make this straightforward; otherwise, a clean one-time payment flow is enough for this phase.
• End-to-end tests that show at least one live card payment, one failed attempt, and, if enabled, a refund, all recorded in logs.

Acceptance is complete when I can compile the React Native build, run the web branch on staging, execute those tests, and see matching records in both our database and Paystack. Clear setup notes and commented code are part of the hand-off so future developers can maintain the integration without starting over.