Sale Loyalty Multi Gift

This module extends sales promotions (loyalty programs) so that one promotion can contain more than one free gift product. When a customer qualifies for a multi-gift reward, the reward wizard opens with a new list of "Loyalty Gift Lines". For each gift line you see the allowed gift products and pick the one you want to give; the list is read-only for adding or deleting rows, so you only choose among the products already configured in the promotion.

When the reward is applied, the system creates one discounted sale order line per gift line, each with a 100% discount and a name like "Free Product - ...". The chosen product is remembered on the order line, so re-applying or updating the reward keeps the same selection. If a product that is not allowed is chosen, an error is raised ("Invalid product to claim.").

The module also changes the reward button behaviour: if there is exactly one claimable reward and it is a multi-gift reward with more than one product per gift line, the wizard opens directly instead of the usual reward selection screen.

It touches sale.order, sale.order.line and the reward wizard, and adds a new wizard model for the gift lines. Salespeople can read the gift configuration; sales managers can fully manage it.