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/RenderGraphModule/RenderGraphCompilationCache.cs

@@ -27,7 +27,7 @@ internal sealed class CachedCompilation
     public readonly List<ResourceBarrier> barriers = new(128);
     
     // Resource state mappings (for barrier generation)
-    public readonly Dictionary<int, ResourceState> resourceStates = new(128);
+    public readonly Dictionary<int, ResourceBarrierData> resourceStates = new(128);
 
     // Real gpu resource
     public readonly List<Handle<GPUResource>> backingResources = new(32);