maskEmail static method
Masks a string leaving visibleEnd characters visible.
e.g. maskEmail("john@example.com") → "j***@example.com"
Implementation
static String maskEmail(String email) {
final parts = email.split('@');
if (parts.length != 2) return email;
final name = parts[0];
final masked =
name.length <= 1 ? name : '${name[0]}${'*' * (name.length - 1)}';
return '$masked@${parts[1]}';
}