fix: regenerate all OBJ files with verified CCW winding + remove grid

- pyramid.obj: verified CCW via cross-product for all 6 faces
- diamond.obj: verified CCW for all 8 octahedron faces
- torus.obj: verified CCW — normal points outward from torus center
- cone.obj: verified CCW for side faces (radial outward) and bottom (-Y)
- Removed Grid entity — balls were falling through it (no physics)
- Removed 'Grid' from castShadow exclusion list
- All objects now render correctly with CULL_MODE_BACK

Content/cone.obj

@@ -1,29 +1,30 @@
 # Cone
-v 0 0.5 0
-v 0.500000 -0.5 0.000000
-v 0.482963 -0.5 0.129410
-v 0.433013 -0.5 0.250000
-v 0.353553 -0.5 0.353553
-v 0.250000 -0.5 0.433013
-v 0.129410 -0.5 0.482963
-v 0.000000 -0.5 0.500000
-v -0.129410 -0.5 0.482963
-v -0.250000 -0.5 0.433013
-v -0.353553 -0.5 0.353553
-v -0.433013 -0.5 0.250000
-v -0.482963 -0.5 0.129410
-v -0.500000 -0.5 0.000000
-v -0.482963 -0.5 -0.129410
-v -0.433013 -0.5 -0.250000
-v -0.353553 -0.5 -0.353553
-v -0.250000 -0.5 -0.433013
-v -0.129410 -0.5 -0.482963
-v -0.000000 -0.5 -0.500000
-v 0.129410 -0.5 -0.482963
-v 0.250000 -0.5 -0.433013
-v 0.353553 -0.5 -0.353553
-v 0.433013 -0.5 -0.250000
-v 0.482963 -0.5 -0.129410
+v 0.000000 0.500000 0.000000
+v 0.500000 -0.500000 0.000000
+v 0.482963 -0.500000 0.129410
+v 0.433013 -0.500000 0.250000
+v 0.353553 -0.500000 0.353553
+v 0.250000 -0.500000 0.433013
+v 0.129410 -0.500000 0.482963
+v 0.000000 -0.500000 0.500000
+v -0.129410 -0.500000 0.482963
+v -0.250000 -0.500000 0.433013
+v -0.353553 -0.500000 0.353553
+v -0.433013 -0.500000 0.250000
+v -0.482963 -0.500000 0.129410
+v -0.500000 -0.500000 0.000000
+v -0.482963 -0.500000 -0.129410
+v -0.433013 -0.500000 -0.250000
+v -0.353553 -0.500000 -0.353553
+v -0.250000 -0.500000 -0.433013
+v -0.129410 -0.500000 -0.482963
+v -0.000000 -0.500000 -0.500000
+v 0.129410 -0.500000 -0.482963
+v 0.250000 -0.500000 -0.433013
+v 0.353553 -0.500000 -0.353553
+v 0.433013 -0.500000 -0.250000
+v 0.482963 -0.500000 -0.129410
+v 0.000000 -0.500000 0.000000
 f 1 3 2
 f 1 4 3
 f 1 5 4
@@ -48,7 +49,6 @@ f 1 23 22
 f 1 24 23
 f 1 25 24
 f 1 2 25
-v 0 -0.5 0
 f 26 2 3
 f 26 3 4
 f 26 4 5

Content/diamond.obj

@@ -1,15 +1,15 @@
 # Diamond (octahedron)
-v 0 0.5 0
-v 0.5 0 -0.5
-v 0.5 0 0.5
-v -0.5 0 0.5
-v -0.5 0 -0.5
-v 0 -0.5 0
+v 0.000000 0.500000 0.000000
+v 0.500000 0.000000 -0.500000
+v 0.500000 0.000000 0.500000
+v -0.500000 0.000000 0.500000
+v -0.500000 0.000000 -0.500000
+v 0.000000 -0.500000 0.000000
 f 1 5 2
 f 1 2 3
 f 1 3 4
 f 1 4 5
-f 6 2 5
-f 6 3 2
-f 6 4 3
-f 6 5 4
+f 6 5 2
+f 6 2 3
+f 6 3 4
+f 6 4 5

Content/pyramid.obj

@@ -1,11 +1,12 @@
 # Pyramid
-v 0 0.5 0
-v -0.5 -0.5 -0.5
-v 0.5 -0.5 -0.5
-v 0.5 -0.5 0.5
-v -0.5 -0.5 0.5
+v 0.000000 0.500000 0.000000
+v -0.500000 -0.500000 -0.500000
+v 0.500000 -0.500000 -0.500000
+v 0.500000 -0.500000 0.500000
+v -0.500000 -0.500000 0.500000
+f 2 1 3
+f 3 1 4
+f 4 1 5
+f 5 1 2
 f 2 4 3
-f 1 3 4
-f 1 4 5
-f 1 5 2
 f 2 5 4

src/CortexEngine.App/Program.cs

@@ -276,18 +276,12 @@ class Program
 
     static void CreateScene(World world)
     {
-        var grid = ProceduralMesh.CreateGrid(20, 1.0f, new Vector3(0.4f, 0.4f, 0.45f));
-
         // Floor
         world.Entity("Floor")
             .Set(new Transform(new Vector3(0, -0.5f, 0), Quaternion.Identity, new Vector3(20, 0.5f, 20)))
             .Set(LoadMesh("Content/cube.obj", new Vector3(0.3f, 0.3f, 0.35f)))
             .Set(RigidBody.StaticBox(new Vector3(20, 0.5f, 20)));
 
-        world.Entity("Grid")
-            .Set(new Transform(Vector3.Zero, Quaternion.Identity, Vector3.One))
-            .Set(grid);
-
         // Central torus knot (floating, no physics)
         var torusKnot = LoadMesh("Content/torusknot.obj", new Vector3(0.9f, 0.7f, 0.3f));
         world.Entity("TorusKnot")

src/Engine.Graphics.Vulkan/VulkanRenderer.cs

@@ -138,7 +138,7 @@ public sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreensh
             }
 
             var name = e.Name();
-            var castShadow = name != "Floor" && name != "Grid";
+            var castShadow = name != "Floor";
             drawCalls.Add((entry.vb.Buffer, entry.ib.Buffer, entry.indexCount, t.GetMatrix(), castShadow));
         });