Per-SKU tiered discounts under one discount code

Allow creating a single discount code that applies different discount amounts to different sets of products/variants (e.g., group A = 10% off, group B = 20% off, group C = 30% off). This would require support for multiple product-level discount rules or a per-product discount mapping within one Advanced Discount Code campaign. The merchant plans to distribute the single code to exclusive customers via Mailchimp.