feat(resource): refactor heap management & suballocation

Major overhaul of GPU resource/heap management:
- Replace resource pooling and upload buffer logic with transient heap/page-based suballocation in ResourceManager.
- Add support for suballocation and heap flags/types, with D3D12 helpers.
- Remove ICommandBuffer.UploadBuffer/UploadTexture; add UpdateSubResources and CopyBuffer, move upload logic to RenderingContext.
- Refactor D3D12ResourceAllocator/Database for suballocation, heap flags, and mapping.
- Standardize on Handle<GPUBuffer> usage.
- Update meshlet/mesh utilities for new allocation handles and memory pools.
- Refactor RenderGraph and docs to use "heap" terminology.
- Use cpuFrame/gpuFrame consistently for frame sync.
- Add s2h.hlsl, s2h_3d.hlsl, s2h_scatter.hlsl shader debug libs.
- Miscellaneous fixes, cleanup, and dependency updates.

BREAKING CHANGE: Resource pooling and upload APIs replaced with new heap/page-based suballocation system. Update all buffer/texture creation and upload code to use new ResourceManager and ICommandBuffer methods.

src/Runtime/Ghost.Graphics.RHI/ICommandBuffer.cs

@@ -185,24 +185,6 @@ public interface ICommandBuffer : IDisposable
     // TODO: This method is not supported yet.
     void DispatchRay();
 
-    /// <summary>
-    /// Uploads the specified data to the buffer represented by the given handle.
-    /// </summary>
-    /// <typeparam name="T">The unmanaged Value space of the elements to upload to the buffer.</typeparam>
-    /// <param name="buffer">A handle to the buffer that will receive the uploaded data.</param>
-    /// <param name="data">A read-only span containing the data to upload to the buffer. The span must contain elements of space
-    /// <typeparamref name="T"/>.</param>
-    void UploadBuffer<T>(Handle<GPUBuffer> buffer, params ReadOnlySpan<T> data)
-        where T : unmanaged;
-
-    /// <summary>
-    /// Uploads texture data to the specified texture resource starting at the given subresource index.
-    /// </summary>
-    /// <param name="texture">The texture resource to which the subresource data will be uploaded. Must be a valid, initialized texture handle.</param>
-    /// <param name="subresources">A reference to the structure containing the subresource data to upload. The data must match the Format and layout expected by the texture.</param>
-    /// Must be greater than zero and not exceed the remaining subresources in the texture.</param>
-    void UploadTexture(Handle<GPUTexture> texture, params ReadOnlySpan<SubResourceData> subresources);
-
     /// <summary>
     /// Copies a specified number of bytes from the source graphics buffer to the destination graphics buffer.
     /// </summary>
@@ -221,4 +203,6 @@ public interface ICommandBuffer : IDisposable
     /// <param name="src">The handle to the source texture from which data will be read.</param>
     /// <param name="srcRegion">The region of the source texture to copy from. If null, the entire texture will be used.</param>
     void CopyTexture(Handle<GPUTexture> dst, TextureRegion? dstRegion, Handle<GPUTexture> src, TextureRegion? srcRegion);
+
+    void UpdateSubResources(Handle<GPUResource> resource, Handle<GPUResource> intermediate, params ReadOnlySpan<SubResourceData> subResources);
 }