VisibilityChangeModal class

Risk-aware confirmation dialog shown before increasing a domain's visibility (private → shared, private → public, or shared → public).

Reducing visibility (public → private, shared → private, public → shared) does NOT show this dialog — those transitions remove access and don't require a warning.

The dialog explains exactly who will gain access and reminds the user that the change is recorded in the audit log for compliance.

Usage:

final confirmed = await VisibilityChangeModal.show(
  context,
  domainName: domain.name,
  from: 'private',
  to: 'public',
);
if (confirmed) { /* proceed */ }