Discount Code API for White Label and Standard Websites#2658

Add an API endpoint to create and manage discount codes for both white label and regular sites. This would enable automated generation of unique promo codes for client retention, welcome offers, and reactivation campaigns.

Such functionality is crucial for agencies and SaaS resellers managing multiple clients and stores. Manual discount creation limits scalability and slows down marketing workflows. An API solution would allow dynamic, event-based coupon generation directly from integrated systems, improving automation, efficiency, and overall customer experience.