Add Maximum Stay Limit to Direct Booking Promo Codes

Problem: Currently, promo codes for direct bookings only allow for a minimum stay limit. This makes it risky to run "BOGO" style offers (e.g., stay 2 nights, get 1 free) because a guest could book a very long stay (e.g., 2 weeks) with the discount, leading to significant revenue loss.

Proposed Solution: Add a 'Maximum Stay' field when creating promo codes to limit the number of nights the discount can be applied to.

Impact: Prevents unintended deep discounts on long-term stays and protects host revenue.

Unlock: Hosts can confidently run aggressive short-term promotions without the risk of losing revenue on long-term bookings.