feat: Add Paystack payment integration

[deepshekhardas]

Fixes #28737

Summary

Adds Paystack payment provider integration for African markets.

Changes

• Added PaymentService.ts for Paystack in packages/app-store/paystack/lib/
• Implements IAbstractPaymentService interface
• Handles payment creation, seat availability checks
• Stores payment metadata with Paystack public key

Features

• Payment creation with booking integration
• Seat availability validation
• Error handling with proper cancellation
• Secure credential management

Implementation

• Uses Prisma for payment record storage
• Implements standard Cal.com payment flow
• Compatible with existing booking system

Testing

• Payment creation flow
• Error handling scenarios
• Seat availability integration

Notes

• Requires Paystack secret and public keys
• Supports multiple currencies based on Paystack configuration

[cubic-dev-ai]

No issues found across 2 files