Add contextual commands

Toolkit.Foundation/AggerateEventArgs.cs

@@ -0,0 +1,12 @@
+namespace Toolkit.Foundation;
+
+public record AggerateEventArgs<TValue> : 
+    IAggerate
+{
+    public object? Key { get; init; }
+
+    public static Aggerate<TValue, TOptions> With<TOptions>(TOptions options) where TOptions : class
+    {
+        return new Aggerate<TValue, TOptions>(options);
+    }
+}