 Behavior:
                
                    Start typing client name to search Portal clients
                    Shows matching clients from Portal database
                    Click to select a client Start typing client name to search Portal clients Shows matching clients from Portal database Click to select a client Default: Leave empty to allow coupon for all clients Purpose: Restrict discount to specific Portal client(s) (e.g., "LOYALTY20" only for VIP clients) Validation: Only applies if coupon is being used by that specific client Requires: Portal plugin and client database to be available