Update onboarding card and post reference survey link

Onboarding form replies don't update candidate cards, forcing manual copying and causing missing emails and survey links. Coordinators get complete cards with survey links within minutes.

Overview

When onboarding form replies don't appear on tracker cards, coordinators waste time and applicants wait for next steps. This flow writes form data, generates usernames/emails, and posts the reference survey link to the card automatically so coordinators have complete records within minutes.