Add completed course purchasers to targeted nurture lists

Completed course orders aren't added to marketing lists, leaving support without purchase context. Add buyers to the correct post-purchase lists so support and campaign managers can act the same day.

Overview

When completed course orders don't map into marketing lists, onboarding sequences get delayed and support lacks purchase context. This flow captures purchasers into the correct post-purchase lists so campaign managers and support can trigger onboarding and respond the same day.