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/Core/RenderOutput.cs

@@ -0,0 +1,85 @@
+using Ghost.Core;
+using Ghost.Graphics.Contracts;
+using Ghost.Graphics.RHI;
+
+namespace Ghost.Graphics.Core;
+
+internal class SwapChainRenderOutput : IRenderOutput
+{
+    private readonly ISwapChain _swapChain;
+
+    public ViewportDesc Viewport
+    {
+        get; set;
+    }
+
+    public RectDesc Scissor
+    {
+        get; set;
+    }
+
+    public SwapChainRenderOutput(ISwapChain swapChain)
+    {
+        _swapChain = swapChain;
+
+        Viewport = new ViewportDesc { Width = swapChain.Width, Height = swapChain.Height, MinDepth = 0, MaxDepth = 1 };
+        Scissor = new RectDesc { Right = swapChain.Width, Bottom = swapChain.Height };
+    }
+
+    public Handle<Texture> GetRenderTarget()
+    {
+        return _swapChain.GetCurrentBackBuffer();
+    }
+
+    public void BeginRender(ICommandBuffer cmd)
+    {
+        cmd.ResourceBarrier(GetRenderTarget().AsResource(), ResourceState.Present, ResourceState.RenderTarget);
+    }
+
+    public void EndRender(ICommandBuffer cmd)
+    {
+        cmd.ResourceBarrier(GetRenderTarget().AsResource(), ResourceState.RenderTarget, ResourceState.Present);
+    }
+
+    public void Present()
+    {
+        _swapChain.Present();
+    }
+}
+
+internal class TextureRenderOutput : IRenderOutput
+{
+    private readonly Handle<Texture> _texture;
+
+    public ViewportDesc Viewport
+    {
+        get; set;
+    }
+
+    public RectDesc Scissor
+    {
+        get; set;
+    }
+
+    public TextureRenderOutput(Handle<Texture> texture)
+    {
+        _texture = texture;
+    }
+
+    public Handle<Texture> GetRenderTarget()
+    {
+        return _texture;
+    }
+
+    public void BeginRender(ICommandBuffer cmd)
+    {
+    }
+
+    public void EndRender(ICommandBuffer cmd)
+    {
+    }
+
+    public void Present()
+    {
+    }
+}