Refactor GPU resource management and rendering pipeline

- Introduced `Handle<T>` and `Identifier<T>` for lightweight, strongly-typed resource identifiers.
- Replaced `BitSet` with `UnsafeBitSet` for improved performance and memory safety.
- Refactored `Mesh` and `Material` into `MeshClass` and `MaterialClass` for better GPU resource handling.
- Added `D3D12ResourceDatabase` to centralize GPU resource tracking and lifecycle management.
- Updated `D3D12ShaderCompiler` to load shaders from disk and dynamically populate constant buffers and textures.
- Enhanced `ICommandBuffer` with new upload operations for buffers and textures.
- Refactored `Vertex` struct for simplified memory layout and better performance.
- Updated `MeshBuilder` and rendering logic to align with new resource and shader structures.
- Added `BindlessDescriptor` support to `TextureHandle` and `BufferHandle`.
- Removed unused classes and performed general cleanup.
- Updated unit tests and demos to reflect the new architecture.

Ghost.Graphics/RenderPasses/MeshRenderPass.cs

@@ -100,9 +100,9 @@ float4 PSMain(PixelInput input) : SV_TARGET
 ";
 
     // High-level bindless objects
-    private Mesh? _mesh;
+    private MeshClass? _mesh;
     private Shader? _shader;
-    private Material? _material;
+    private MaterialClass? _material;
     private Texture2D[]? _textures;
 
     // Texture file paths for this demo
@@ -118,7 +118,7 @@ float4 PSMain(PixelInput input) : SV_TARGET
         _mesh = MeshBuilder.CreateCube(0.75f);
         _mesh.UploadMeshData();
 
-        _shader = new Shader(_HLSL_SOURCE);
+        _shader = new ShaderData(_HLSL_SOURCE);
         _material = new Material(_shader);
 
         _textures = new Texture2D[_textureFiles.Length];