Seed the estimate's lines from its appointment type's default services. Rebuilds the retired appointment-services "populate-defaults" onto the estimate line: each active default service becomes a Pending line. The dispense fee is charged once per unique inventory item across the whole estimate (existing lines count), matching the old behaviour. No-op (ItemsAdded = 0) when the estimate has no appointment, the appointment has no type, or the type has no active default services.