feat(rhi)!: refactor resource handles to GPUTexture/GPUBuffer

Refactored all graphics resource handles to use Handle<GPUTexture> and Handle<GPUBuffer> instead of Handle<Texture> and Handle<GraphicsBuffer>. Updated all APIs, interfaces, and implementations to use the new types, including ICommandBuffer, IResourceAllocator, ISwapChain, IRenderOutput, IRenderGraphBuilder, and related classes. Introduced TempJobAllocator for frame-latency-aware allocations. Updated ResourceHandleExtensions for new conversions. Performed minor code cleanups and removed the empty ClusterLod.cs file.

BREAKING CHANGE: All usages of Handle<Texture> and Handle<GraphicsBuffer> are replaced with Handle<GPUTexture> and Handle<GPUBuffer>. This affects all APIs and resource management code. Callers must update their code to use the new handle types.

src/Test/Ghost.Graphics.Test/Windows/GraphicsTestWindow.xaml.cs

@@ -81,7 +81,7 @@ public sealed partial class GraphicsTestWindow : Window
         _world.EntityManager.SetComponent(cameraEntity, new Camera
         {
             swapChainIndex = 0,
-            depthTarget = Handle<Texture>.Invalid,
+            depthTarget = Handle<GPUTexture>.Invalid,
             nearClipPlane = 0.1f,
             farClipPlane = 1000.0f,
             focalLength = 50.0f,