Add Phase 4 tests for DescriptorHeap, Shader, RootSignature, PipelineState, Views

- DescriptorHeap: CBV_SRV_UAV, Sampler, RTV, DSV, HandleIncrementSize
- Shader: Vertex/Pixel/Compute profiles
- RootSignature: Empty, with CBV parameter
- PipelineState: Graphics/Compute pipeline desc defaults
- Views: RTV, DSV, CBV descriptor heaps, handle increment
- All 54 tests pass

tests/RHI/D3D12/test_pipeline_state.cpp

@@ -1,5 +1,42 @@
 #include "fixtures/D3D12TestFixture.h"
 
 TEST_F(D3D12TestFixture, PipelineState_Placeholder) {
-    ASSERT_TRUE(true);
+    ASSERT_NE(GetDevice(), nullptr);
+}
+
+TEST_F(D3D12TestFixture, PipelineState_GraphicsPipelineDescDefaults) {
+    D3D12_GRAPHICS_PIPELINE_STATE_DESC psoDesc = {};
+    psoDesc.InputLayout = {};
+    psoDesc.pRootSignature = nullptr;
+    psoDesc.VS = {};
+    psoDesc.PS = {};
+    psoDesc.DS = {};
+    psoDesc.HS = {};
+    psoDesc.GS = {};
+    psoDesc.StreamOutput = {};
+    psoDesc.BlendState = {};
+    psoDesc.SampleMask = UINT_MAX;
+    psoDesc.RasterizerState = {};
+    psoDesc.DepthStencilState = {};
+    psoDesc.PrimitiveTopologyType = D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE;
+    psoDesc.NumRenderTargets = 1;
+    psoDesc.RTVFormats[0] = DXGI_FORMAT_R8G8B8A8_UNORM;
+    psoDesc.DSVFormat = DXGI_FORMAT_D32_FLOAT;
+    psoDesc.SampleDesc.Count = 1;
+    psoDesc.SampleDesc.Quality = 0;
+    
+    EXPECT_EQ(psoDesc.PrimitiveTopologyType, D3D12_PRIMITIVE_TOPOLOGY_TYPE_TRIANGLE);
+    EXPECT_EQ(psoDesc.NumRenderTargets, 1);
+}
+
+TEST_F(D3D12TestFixture, PipelineState_ComputePipelineDescDefaults) {
+    D3D12_COMPUTE_PIPELINE_STATE_DESC psoDesc = {};
+    psoDesc.pRootSignature = nullptr;
+    psoDesc.CS = {};
+    psoDesc.NodeMask = 0;
+    psoDesc.CachedPSO = {};
+    psoDesc.Flags = D3D12_PIPELINE_STATE_FLAG_NONE;
+    
+    EXPECT_EQ(psoDesc.NodeMask, 0);
+    EXPECT_EQ(psoDesc.Flags, D3D12_PIPELINE_STATE_FLAG_NONE);
 }