feat(physics): added area & inertia calculations for the shape and circles

Engine.Core/Primitives/Circle.cs

@@ -34,6 +34,16 @@ public readonly struct Circle(Vector2D center, float radius) : IEquatable<Circle
     /// </summary>
     public readonly float Diameter => 2f * Radius;
 
+    /// <summary>
+    /// Gets the area of the <see cref="Circle"/>.
+    /// </summary>
+    public readonly float Area => Math.Pi * RadiusSquared;
+
+    /// <summary>
+    /// Gets the geometric interia of the <see cref="Circle"/>.
+    /// </summary>
+    public readonly float GeometricInertia => .5f * RadiusSquared;
+
     /// <summary>
     /// A predefined unit <see cref="Circle"/> with a center at the origin and a radius of 1.
     /// </summary>