changePassword now calls authService.revokeOtherSessions() after the
password is updated and emits a LOGOUT audit with reason=password_change.
POST /api/users/{id}/force-logout (ADMIN_USER permission) revokes all
sessions for the target user and emits ADMIN_FORCE_LOGOUT audit. Returns
{"revokedCount": N} with 200.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>