Add Ehwrj clean-room live map

src/Ehwrj.App/ViewModels/ObservableObject.cs

@@ -0,0 +1,27 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace Ehwrj.App.ViewModels;
+
+public abstract class ObservableObject : INotifyPropertyChanged
+{
+    public event PropertyChangedEventHandler? PropertyChanged;
+
+    protected bool SetProperty<T>(ref T field, T value, [CallerMemberName] string? propertyName = null)
+    {
+        if (EqualityComparer<T>.Default.Equals(field, value))
+        {
+            return false;
+        }
+
+        field = value;
+        OnPropertyChanged(propertyName);
+        return true;
+    }
+
+    protected void OnPropertyChanged([CallerMemberName] string? propertyName = null)
+    {
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}
+