feat: production-ready Stripe PaymentIntent integration (#1)

[Ishant5436]

Integration of the Stripe SDK for production-grade payment orchestration.

Technical details:

• Atomic PaymentIntents: Fully implemented the PaymentIntents lifecycle using the Node.js SDK, ensuring synchronous state management for financial transactions.
• Data Validation: Enforced strict integer-based amount validation to prevent precision-loss during currency conversion.
• Exception Mapping: Developed a robust error mapping layer that translates Stripe API exceptions into stable internal error codes for front-end consumption.
• Verification: Includes a dedicated test suite in apps/api/src/tests/payment.test.js.

Settlement Information:

• Solana: 2WktXRjaQ4GKhj6FJhUSndTBLVjxrk43TQwyywehneDA

[BossChaos]

Code Review

PR: feat: production-ready Stripe PaymentIntent integration (#1) by @Ishant5436

• 🔒 Payment integration — needs security review

Wallet: 0xdaE5d307339074A24F579dB48e7c639359D94904

Code review for SecureBananaLabs bug-bounty