Support for short-term length-of-stay discounts for Vrbo

Currently, Hospitable only supports weekly and monthly length-of-stay discounts for Vrbo. Because Vrbo disables discount editing in their dashboard when connected via the Partner connection, hosts are unable to set shorter length-of-stay discounts (such as 2-night or 3-night discounts) manually. Hosts need the ability to create and sync these shorter discounts directly from Hospitable to maintain pricing consistency and control.