Add DiplomaOrigin (Binnenlands/Buitenlands) to the Registration aggregate and
submit command, and thread it through the process-start port so the workflow's
DMN can route on it (ADR proposal #100). Failing Workflow Client test asserts the
diplomaOrigin start variable; the client takes the origin but does not emit it yet.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
