cull(engine-cleanup): pass-8 phase-2 cascade round 1

[trim] fully-unreachable files deleted: 6
[trim] files edited: 55, files deleted: 0, nodes removed: 244
[type-trim] files edited: 1, types removed: 1

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.BattleEngine/Engine/HandControl.cs

@@ -86,11 +86,6 @@ public abstract class HandControl
 		return _handState == HandState.Focus;
 	}
 
-	public bool IsVisibleHand()
-	{
-		return _handVisible == HandVisible.Visible;
-	}
-
 	public void SetHandPosition()
 	{
 		Transform.localPosition = BaseHandPos;