Free Gift Pool

Products eligible to be given away as the cart free gift. The storefront gives away the FIRST product here that still has inventory, so the order of this collection is the priority order — drag to change which gift is offered first. The checkout discount function matches this collection by id, so this collection is the single source of truth for what is giveable. Do NOT delete and recreate it: the id is compiled into the discount function, and a new id turns the feature off. See docs/features/cart-progress.md in martie-site.