SubmitRegistration creates the aggregate, persists it, starts the registratie
process via the Workflow Client, records the instance id and upserts. OpenZaakWorker
loads the correlated registration, opens a zaak via the ACL, attaches it and saves;
an unknown registration throws (job redelivered), and an already-opened zaak short-
circuits without opening a second one (§8.6).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>