testing building some core systems

- serialization
- chunks
- parralelfor test

Nerfed.Runtime/Scene/SceneRelationAttribute.cs

@@ -0,0 +1,10 @@
+namespace Nerfed.Runtime.Scene;
+
+/// <summary>
+/// Marks an unmanaged struct as a serializable scene relation kind.
+/// Both endpoints and the data payload will be saved/loaded by the scene system.
+/// The <see cref="Components.ChildParentRelation"/> hierarchy is handled separately via
+/// <see cref="SceneEntityData.ParentId"/> and should NOT be marked with this attribute.
+/// </summary>
+[AttributeUsage(AttributeTargets.Struct, Inherited = false)]
+public sealed class SceneRelationAttribute : Attribute { }