Coupons multi gift in sales

When a promotion is configured with the multi gift reward type, this module makes Odoo create one free product line per reward rule on the sales order. Each line is marked as a reward line, gets a 100% discount, and shows the text "Free Product" followed by the product name.

• On the sales order, the reward lines are linked to the promotion and to the specific reward rule, so Odoo can update or remove them correctly when the order changes.
• If a reward rule offers a choice of products, the chosen product is remembered on the line and reused when the promotion is recalculated.
• The module keeps valid multi gift reward lines from being deleted when promotions are refreshed, and it removes only the lines that no longer belong to an applicable promotion.
• On the promotion itself, the number of sales orders using it is counted from the linked order lines, and the button to view those sales orders shows only confirmed orders (not draft, sent, or cancelled).
• Salespeople can read the reward product line configuration, while sales managers can create, edit, and delete it.

The module extends coupon.program, sale.order, and sale.order.line.