Notifies the team LEAD with FINALIST_WITHDRAWN (in-app + email) when an admin
withdraws a grand-finale slot via adminDecline, unconfirm, or unenroll.
For unenroll, only notifies when a CONFIRMED confirmation existed before deletion.
Adds finalist-withdrawal.test.ts (4 tests) covering all three paths.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
