Add attribute system with core stats and gameplay components

GameCore/Combat/EffectExecutionSystem.cs

@@ -0,0 +1,12 @@
+using GameCore.ECS;
+using GameCore.ECS.Interfaces;
+
+namespace GameCore.Combat;
+
+public class EffectExecutionSystem : ISystem
+{
+    public void Update(World world, float deltaTime)
+    {
+        throw new NotImplementedException();
+    }
+}