RHI: Add Compute/Dispatch unit tests (P1-7) and fix shader type bugs

Bug fixes:
- D3D12Shader::Compile: Set m_type based on target string (cs_/vs_/ps_/gs_)
- OpenGLShader::Compile: Parse target parameter to determine shader type
- OpenGLShader::CompileCompute: Set m_type = ShaderType::Compute
- D3D12CommandList::SetPipelineState: Use correct PSO handle for Compute

New tests (test_compute.cpp, 8 tests):
- ComputeShader_Compile_ValidShader
- ComputeShader_GetType_ReturnsCompute
- ComputeShader_Shutdown_Invalidates
- PipelineState_SetComputeShader
- PipelineState_HasComputeShader_ReturnsTrue
- PipelineState_GetType_Compute
- PipelineState_EnsureValid_Compute
- CommandList_Dispatch_Basic

Test results: 232/232 passed (D3D12: 116, OpenGL: 116)

engine/src/RHI/D3D12/D3D12CommandList.cpp

@@ -178,7 +178,13 @@ void D3D12CommandList::AliasBarrier(ID3D12Resource* beforeResource, ID3D12Resour
 
 void D3D12CommandList::SetPipelineState(RHIPipelineState* pso) {
     if (!pso) return;
-    SetPipelineStateInternal(static_cast<ID3D12PipelineState*>(pso->GetNativeHandle()));
+    
+    if (pso->GetType() == PipelineType::Compute) {
+        D3D12PipelineState* d3d12Pso = static_cast<D3D12PipelineState*>(pso);
+        SetPipelineStateInternal(d3d12Pso->GetComputePipelineState());
+    } else {
+        SetPipelineStateInternal(static_cast<ID3D12PipelineState*>(pso->GetNativeHandle()));
+    }
 }
 
 void D3D12CommandList::SetPipelineState(ID3D12PipelineState* pso) {