Fix Existing Payment System & Add Payment/Promotion Features

I have an existing Telegram Signal Copier web application built with Python/Flask, HTML, CSS and JavaScript. The project is already live and the complete source code is maintained in a private GitHub repository. I am looking for an experienced developer to make several targeted updates and fixes to the existing system. IMPORTANT: This is NOT a new application and I do not want the payment system rebuilt from scratch. The existing payment framework/code should be inspected, preserved and properly completed/fixed. Main tasks 1. USD as the default payment currency - Remove the forced Naira/NGN payment prompt. - USD should be the default currency presented to customers. - The existing pricing structure should remain intact unless a change is specifically agreed upon. 2. Paystack - The project already contains Paystack/payment-related framework code. - Inspect the existing implementation and activate/fix the Paystack payment flow rather than creating an unnecessary new system. - Ensure successful Paystack payments are properly verified on the backend. - Ensure the correct license is generated/activated after successful payment. - Handle failed, cancelled and abandoned payments properly. - Verify that users cannot receive a license simply by manipulating the frontend/payment response. 3. Existing Flutterwave payment - Preserve the existing Flutterwave functionality. - Ensure Flutterwave continues working after the changes. - Do not break the current payment verification process while implementing Paystack. 4. Coupon/Discount system Add a coupon system that can be managed by my team. The admin/team should be able to: - Create coupon codes - Edit coupon codes - Enable/disable coupons - Set percentage or fixed discounts - Set coupon expiry dates - Set usage limits if practical - Create promotional campaigns such as: BLACKFRIDAY CYBERMONDAY CHRISTMAS ANNIVERSARY Other future campaigns Coupon validation and discount calculation must happen securely on the backend, not only through JavaScript/frontend code. 5. Discord Add our Discord community link under the existing "Contact Us" / contact section. Very important development requirements: - Work from the existing private GitHub repository. - Do not rebuild the application unnecessarily. - Before making changes, create a separate Git branch/backup so the existing working version can always be restored. - Do not delete or replace existing files/functions unless necessary. - Preserve the existing Telegram signal copier, licensing, authentication, session management and EA functionality. - Preserve existing Flutterwave functionality. - Use clean, maintainable code. - Keep sensitive API keys/secrets out of the frontend and GitHub. - All payment verification must be performed securely on the backend. - Clearly document the changes made. - Push the completed changes to GitHub. - Do not consider the job complete until the payment/subscription flows have been tested. Acceptance testing Before completion, I want the developer to demonstrate/test: - Paystack successful payment - Paystack failed/cancelled payment - Flutterwave successful payment - Flutterwave failed/cancelled payment - Correct license creation after successful payment - Coupon application and discount calculation - Expired/disabled coupon rejection - Existing login, licensing and session functionality still working Deliverables: - Fully working updated application - Updated GitHub repository - Payment/subscription flows working correctly - Paystack activated/fixed - Flutterwave preserved and working - USD as default payment currency - Editable coupon system - Discord contact link - Brief documentation of changes - Confirmation that existing functionality was tested after the update Developer requirements: Please only apply if you are comfortable working with an existing Flask/Python application, JavaScript frontend, payment gateways (especially Paystack and Flutterwave), REST APIs, databases and Git/GitHub. When applying, please briefly explain: - Your experience with Paystack integration. - Your experience with Flutterwave. - Your experience fixing payment flows in existing applications. - How you would safely approach modifying an existing production codebase without breaking it. I prefer a developer who will first inspect the existing codebase and explain what is already implemented before making changes.