ContactRepositoryTest: Add tests covering find/create/update/delete

Verify the statements `ContactRepository` issues against a mocked
database connection, serving the ORM queries it builds internally by
returning SQLite-backed PDOStatements the ORM hydrates into models.
Covers the differential address update and the escalation cleanup on
deletion; rotation handling is delegated to and covered by
`RotationRepositoryTest`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: nilmerg