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/RHI/ISwapChain.cs

@@ -49,7 +49,7 @@ public interface ISwapChain : IDisposable
     /// <summary>
     /// Gets all back buffer textures
     /// </summary>
-    /// <returns>All back buffer textures</returns>
+    /// <returns>AlowBufferAndTexture back buffer textures</returns>
     ReadOnlySpan<Handle<Texture>> GetBackBuffers();
 
     /// <summary>