Sale Loyalty Order Suggestion Multi Gift

This module builds on two existing promotion modules to make multi-gift rewards appear in the promotion suggestions shown on a sale order.

When Odoo looks for available promotions for a sale order, it now also includes programs whose reward type is 'multi_gift' and whose reward products include the product currently being sold. This means salespeople can see and pick multi-gift promotions directly from the order line suggestion area.

When a user applies a multi-gift reward through the reward wizard, the module first applies the loyalty rule lines to the order. After the standard reward application, it checks each selected gift line. If the selected gift product is not one of the products required by the promotion rules and no units of that product are meant to be included, it removes the corresponding quantity from the order line. If the whole line quantity matches the quantity to remove, the line is deleted; otherwise the quantity is reduced.

The module also changes how the selected gift is pre-filled in the gift selection wizard: if the wizard is for a multi-gift reward and the product being sold is among the available gifts, that product is automatically selected as the gift.

It touches the sale order model and the loyalty reward wizards, and it works together with the promotion suggestion and multi-gift modules.