Render graph: native pass merging & heap-based aliasing

Major architecture upgrade:
- Add native render pass merging (hardware pass grouping, load/store op inference)
- Implement heap-based aliasing for textures & buffers (D3D12-style)
- Unify resource model: buffers and textures in one registry
- Extend builder API for buffer creation/usage, access flags, hints
- Improve barrier/state tracking (buffer hints, indirect argument state)
- Update caching, hashing, and debug output for new model
- Add enums/structs: AttachmentLoadOp, StoreOp, BufferHint, etc.
- D3D12 backend: support named resources, temp upload buffers, correct heap usage
- Update docs, benchmarks, and project files for new features

Brings render graph closer to AAA engine standards, enabling efficient memory usage, lower driver overhead, and a more flexible API.

Ghost.Graphics/D3D12/D3D12DescriptorHeap.cs

@@ -138,7 +138,7 @@ internal unsafe struct D3D12DescriptorHeap : IDisposable
         }
 
         // NOTE: In dynamic allocation, we use arena-style allocation without freeing.
-        // We reset the offset at the beginning of each frame instead.
+        // We reset the Offset at the beginning of each frame instead.
 
         lock (_lock)
         {