feat(meshlet): refactor meshlet pipeline and add render pass

Refactor meshlet data structures to use packed uint triangle indices, update meshlet cooking and upload logic, and align HLSL mesh shader. Add MeshRenderPass with bindless rendering and blit support. Improve RenderExtractionSystem, RootSignatureLayout, and TestRenderPipeline. Update GraphicsTestWindow for new pipeline and meshlet logic. Includes code cleanups and comments.

src/Runtime/Ghost.Engine/Systems/RenderExtractionSystem.cs

@@ -78,7 +78,6 @@ public class RenderExtractionSystem : ISystem
         ref var cameraQuery = ref systemAPI.World.ComponentManager.GetEntityQueryReference(_cameraQueryID);
         ref var meshQuery = ref systemAPI.World.ComponentManager.GetEntityQueryReference(_meshQueryID);
 
-        // TODO: We should extract the render record for each camera because different cameras may have different culling results.
         foreach (var (cam, camLtw) in cameraQuery.GetComponentIterator<Camera, LocalToWorld>())
         {
             ref readonly var camRef = ref cam.Get();
@@ -108,6 +107,7 @@ public class RenderExtractionSystem : ISystem
                     ref readonly var meshInstance = ref meshInstances[i];
                     if ((meshInstance.renderingLayerMask & camRef.renderingLayerMask) == 0u)
                     {
+                        // Not in the same rendering layer, skip.
                         continue;
                     }
 
@@ -117,6 +117,7 @@ public class RenderExtractionSystem : ISystem
                     var camPosition = camLtwRef.matrix.c3.xyz;
                     var distance = math.distance(meshPosition, camPosition);
 
+                    // TODO: Use bounding sphere or AABB for better culling. Currently it just uses the pivot point which can cause popping when the pivot is far from the actual geometry.
                     if (distance < camRef.nearClipPlane || distance > camRef.farClipPlane)
                     {
                         continue;