Add attribute system with core stats and gameplay components

GameCore/Events/SpawnEntityEvent.cs

@@ -0,0 +1,20 @@
+using GameCore.ECS;
+using GameCore.Events.Interfaces;
+using GameCore.Math;
+
+namespace GameCore.Events;
+
+public readonly struct SpawnEntityEvent(
+    string archetypeId,
+    Vector3 position,
+    Vector3 rotation,
+    Entity owner,
+    Vector3? initialVelocity = null)
+    : IEvent
+{
+    public readonly string ArchetypeId = archetypeId;
+    public readonly Vector3 Position = position;
+    public readonly Vector3 Rotation = rotation;
+    public readonly Entity Owner = owner;
+    public readonly Vector3? InitialVelocity = initialVelocity;
+}