A curator on a person's page can now seed a timeline event from that
person: a gated link to #781's /zeitstrahl/events/new?personId={id},
which prefills the person and returns to /persons/{id} on save. Hidden
for a Reader. New i18n key person_add_event in de/en/es.
Refs #842
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
