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.Core/Graphics/PipelineState.cs

@@ -0,0 +1,84 @@
+namespace Ghost.Core.Graphics;
+
+public enum ZTest
+{
+    Disabled,
+    Less,
+    LessEqual,
+    Equal,
+    GreaterEqual,
+    Greater,
+    NotEqual,
+    Always
+}
+
+public enum ZWrite
+{
+    Off,
+    On
+}
+
+public enum Cull
+{
+    Off,
+    Front,
+    Back
+}
+
+public enum Blend
+{
+    Opaque,
+    Alpha,
+    Additive,
+    Multiply,
+    PremultipliedAlpha
+}
+
+[Flags]
+public enum ColorWriteMask
+{
+    None = 0,
+    Red = 1 << 0,
+    Green = 1 << 1,
+    Blue = 1 << 2,
+    Alpha = 1 << 3,
+    All = Red | Green | Blue | Alpha
+}
+
+public struct PipelineState
+{
+    public ZTest ZTest
+    {
+        get; set;
+    }
+
+    public ZWrite ZWrite
+    {
+        get; set;
+    }
+
+    public Cull Cull
+    {
+        get; set;
+    }
+
+    public Blend Blend
+    {
+        get; set;
+    }
+
+    public ColorWriteMask ColorMask
+    {
+        get; set;
+    }
+
+
+    public static PipelineState Default => new PipelineState
+    {
+        ZTest = ZTest.LessEqual,
+        ZWrite = ZWrite.On,
+        Cull = Cull.Back,
+        Blend = Blend.Opaque,
+        ColorMask = ColorWriteMask.All
+    };
+}