feat: OnFirstActiveFrame of Engine.Core

Game/Behaviours/MovementBoxBehaviour.cs

@@ -32,7 +32,7 @@ public class MovementBoxBehaviour(Keys Up, Keys Down, float High, float Low, flo
         GameObject.Transform.Position = new Vector2(GameObject.Transform.Position.X, MathF.Max(MathF.Min(GameObject.Transform.Position.Y, High), Low));
     }
 
-    protected override void OnInitialize()
+    protected override void OnFirstActiveFrame(GameTime time)
     {
         if (!BehaviourController.TryGetBehaviour<IKeyboardInputs>(out var behaviourResult))
             throw new Exception($"{nameof(IKeyboardInputs)} is missing on ${GameObject.Name}.");