refactor: address PR review feedback on meshlet LOD system

- Remove WORK_SUMMARY.md
- Use Debug.Assert for stride validation in ClodBuilder
- Fix ClodBuilder.Build return value after cluster disposal
- Update ClodPartition to accept AllocationHandle for return collections
- Standardize on camelCase for public fields in ClodConfig, ClodMesh, ClodBounds, etc.
- Remove redundant Resize calls where capacity suffices or Add is used
- Enforce stack allocator usage for internal temporary collections
- Ensure proper allocator propagation for collections returned from methods

src/Runtime/Ghost.Graphics/Meshlet/ClodMesh.cs

@@ -1,16 +1,41 @@
+using System;
+using Ghost.MeshOptimizer;
+using Misaki.HighPerformance;
+
 namespace Ghost.Graphics.Meshlet;
 
 public unsafe struct ClodMesh
 {
+    public float* vertexPositions;
+    public nuint vertexCount;
+    public nuint vertexPositionsStride;
+
+    public float* vertexAttributes;
+    public nuint vertexAttributesStride;
+    public float* attributeWeights;
+    public nuint attributeCount;
+
+    public uint* indices;
+    public nuint indexCount;
+
+    public byte* vertexLock;
+    public uint attributeProtectMask;
+}
+
+public struct ClodGroup
+{
+    public int depth;
+    public ClodBounds simplified;
+}
+
+public unsafe struct ClodCluster
+{
+    public int refined;
+    public ClodBounds bounds;
+
     public uint* indices;
     public nuint indexCount;
     public nuint vertexCount;
-    public float* vertexPositions;
-    public nuint vertexPositionsStride;
-    public float* vertexAttributes;
-    public nuint vertexAttributesStride;
-    public byte* vertexLock;
-    public float* attributeWeights;
-    public nuint attributeCount;
-    public uint attributeProtectMask;
 }
+
+public unsafe delegate int ClodOutputDelegate(void* context, ClodGroup group, ClodCluster* clusters, nuint clusterCount);