Refactor pipeline state and render output abstractions

- Replace old pipeline enums/structs with new strongly-typed PipelineState and enums (ZTest, ZWrite, Cull, Blend, ColorWriteMask)
- Redesign pipeline keying: introduce 128-bit GraphicsPipelineKey, MaterialPipelineKey, and PassPipelineKey for robust PSO caching
- Replace IRenderTargetStrategy with IRenderOutput; add SwapChainRenderOutput and TextureRenderOutput
- Update renderer and window code to use new render output abstraction and handle viewport/scissor updates
- Make ShaderPass a readonly struct and Shader a struct; use ID-based pass lookup for efficiency
- Materials now support per-pass pipeline overrides with new keying
- Add defensive checks in D3D12CommandBuffer; update D3D12PipelineLibrary for new keying/state
- Move test shader to test.gsdef and update for new pipeline state syntax
- Remove obsolete files/interfaces and perform general code cleanups
- Update all usages and parsing logic for new pipeline state system

Ghost.Graphics/D3D12/D3D12Renderer.cs

@@ -22,7 +22,7 @@ internal class D3D12Renderer : IRenderer
     // NOTE: Testing only.
     private readonly MeshRenderPass _pass;
 
-    public IRenderTargetStrategy? RenderTargetStrategy
+    public IRenderOutput? RenderOutput
     {
         get; set;
     }
@@ -47,31 +47,31 @@ internal class D3D12Renderer : IRenderer
 
     public Result Render(ICommandAllocator commandAllocator)
     {
-        if (RenderTargetStrategy is null)
+        if (RenderOutput is null)
         {
             return Result.Failure("Render target strategy is not set.");
         }
 
-        var target = RenderTargetStrategy.GetRenderTarget();
+        var target = RenderOutput.GetRenderTarget();
         if (target.IsInvalid)
         {
             return Result.Failure("Render target is invalid.");
         }
 
         _commandBuffer.Begin(commandAllocator);
-        RenderTargetStrategy.BeginRender(_commandBuffer);
+        RenderOutput.BeginRender(_commandBuffer);
 
         // NOTE: Temperary solution: render directly to the swap chain back buffer if available.
         // HACK: This is hard coded for testing purposes only.
 
-        var error = RenderScene(target, RenderTargetStrategy.Viewport, RenderTargetStrategy.Scissor);
+        var error = RenderScene(target, RenderOutput.Viewport, RenderOutput.Scissor);
         if (error != ErrorStatus.None)
         {
             _commandBuffer.End();
             return Result.Failure(error);
         }
 
-        RenderTargetStrategy.EndRender(_commandBuffer);
+        RenderOutput.EndRender(_commandBuffer);
         var r = _commandBuffer.End();
         if (r.IsFailure)
         {
@@ -79,7 +79,7 @@ internal class D3D12Renderer : IRenderer
         }
 
         _graphicsEngine.Device.GraphicsQueue.Submit(_commandBuffer);
-        RenderTargetStrategy.Present();
+        RenderOutput.Present();
 
         return Result.Success();
     }