isSubsetOf method
Checks if this value is less than or equal to another (⊑).
Implementation
@override
bool isSubsetOf(IntervalDomain other) {
if (isBottom) return true;
if (other.isTop) return true;
final minOk = other.min == null || (min != null && min! >= other.min!);
final maxOk = other.max == null || (max != null && max! <= other.max!);
return minOk && maxOk;
}