Sale Coupon Automatic free product as normal

When you set up a promotion that rewards a free product, Odoo normally requires that product to already be on the order before the coupon can be applied. This module removes that requirement.

On the promotion form (coupon.program), a new option "Add if missing" appears next to the reward product settings. It is only visible when the reward type is a product and the promotion uses a coupon code.

When this option is enabled: - The reward product is added automatically to the sales order when the coupon code is entered, even if the customer did not add it. - If the product is already on the order but in a smaller quantity than the reward quantity, only the missing quantity is added. - The promotion can be found and applied based on the quantities of the eligible products already ordered, taking the reward quantity into account. - The check that the reward product must be present in the order lines is bypassed for these promotions.

The module touches the coupon.coupon, coupon.program, coupon.reward and sale.order models. It does not add new menus or reports; the new setting is added directly to the existing promotion configuration screen.