Coupons administration tab

Platform administrators get a new Coupons tab under Settings ▸ Administration, next to the Plugin Catalog. It lists every coupon code live — what each unlocks, its price, validity window, and how often it has been redeemed — with one click to open a coupon for editing or deletion and a button to create a new code with the standard form. No more hand-crafting nodes under Admin/Coupons to run a promotion.