Refactor error handling: use Error enum, update APIs

Replaces ErrorStatus with Error across all systems for consistency.
Renames ResourceBarrierData fields to camelCase.
Adds BindlessAccess enum and updates GetBindlessIndex API.
Updates method signatures, result types, and error checks.
Modernizes HLSL mesh shader syntax and fixes naming.
Improves code style and updates comments for clarity.

Ghost.Graphics/D3D12/D3D12Renderer.cs

@@ -68,7 +68,7 @@ internal class D3D12Renderer : IRenderer
         // HACK: This is hard coded for testing purposes only.
 
         var error = RenderScene(target, RenderOutput.Viewport, RenderOutput.Scissor);
-        if (error != ErrorStatus.None)
+        if (error != Error.None)
         {
             _commandBuffer.End();
             return Result.Failure(error);
@@ -88,7 +88,7 @@ internal class D3D12Renderer : IRenderer
     }
 
     // TODO: A proper render graph integration.
-    private ErrorStatus RenderScene(Handle<Texture> target, ViewportDesc viewport, RectDesc rect)
+    private Error RenderScene(Handle<Texture> target, ViewportDesc viewport, RectDesc rect)
     {
         // NOTE: Testing only.
         var ctx = new RenderingContext(_graphicsEngine, _commandBuffer);
@@ -116,7 +116,7 @@ internal class D3D12Renderer : IRenderer
         //_commandBuffer.EndRenderPass();
         _frameIndex++;
 
-        return ErrorStatus.None;
+        return Error.None;
     }
 
     public void Dispose()