Refactor RenderGraph barrier/state tracking system

Major overhaul of resource barrier and state tracking in RenderGraph:
- Introduce ResourceBarrierData for explicit (layout, access, sync) tracking.
- Separate aliasing and transition barriers; explicit aliasing support.
- Remove BufferHint; infer buffer usage from BufferUsage flags.
- Update TextureAccess/BufferAccess to include usage requirements.
- Improve enums (BarrierSync, BarrierAccess, BarrierLayout) for D3D12 alignment.
- Update D3D12CommandBuffer to use new barrier data and error handling.
- Make D3D12DescriptorHeap a class; add ReleaseSampler to IResourceDatabase.
- Reset resource pools and aliasing managers each frame.
- Batch and flush barriers efficiently per pass.
- Update HLSL mesh shader macros to [NumThreads].
- Remove obsolete code and improve documentation.
This refactor improves correctness, extensibility, and prepares for advanced features.

Ghost.Graphics/RHI/IResourceDatabase.cs

@@ -110,6 +110,12 @@ public interface IResourceDatabase : IDisposable
     /// <returns>true if a sampler with the given identifier exists; otherwise, false.</returns>
     bool TryGetSampler(ref readonly SamplerDesc desc, out Identifier<Sampler> id);
 
+    /// <summary>
+    /// Releases the sampler associated with the specified identifier and frees any resources allocated to it.
+    /// </summary>
+    /// <param name="id">The identifier of the sampler to release. Must reference a valid, existing sampler.</param>
+    void ReleaseSampler(Identifier<Sampler> id);
+
     /// <summary>
     /// Adds a mesh to the resource database and returns its handle.
     /// </summary>