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/Shim/UnityEngine/UnityShim.cs

@@ -271,7 +271,6 @@ namespace UnityEngine
         public int sortingOrder { get; set; }
     }
     public class MeshRenderer : Renderer { }
-    public class SkinnedMeshRenderer : Renderer { }
     public class SpriteRenderer : Renderer { public Color color { get; set; } }
     public class MeshFilter : Component { public Mesh mesh { get; set; } public Mesh sharedMesh { get; set; } }
     public class ParticleSystem : Component