Add YAML/Presamp Watcher - #2146

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-dotnet@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Nullability of reference types in type of 'event PropertyChangedEventHandler UOto.PropertyChanged' doesn't match implicitly implemented member 'event PropertyChangedEventHandler? INotifyPropertyChanged.PropertyChanged'.

Nullability of reference types in type of parameter 'other' of 'int PitchPoint.CompareTo(PitchPoint other)' doesn't match implicitly implemented member 'int IComparable<PitchPoint>.CompareTo(PitchPoint? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'int UNote.CompareTo(object obj)' doesn't match implicitly implemented member 'int IComparable.CompareTo(object? obj)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'other' of 'bool UExpressionDescriptor.Equals(UExpressionDescriptor other)' doesn't match implicitly implemented member 'bool IEquatable<UExpressionDescriptor>.Equals(UExpressionDescriptor? other)' (possibly because of nullability attributes).

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.