Fix GPU state issue - make device non-static per test

- Each test now creates its own D3D12 device, command queue, allocator, and command list
- Properly cleanup in TearDown to avoid GPU state issues
- All 29 tests now pass

tests/RHI/D3D12/fixtures/D3D12TestFixture.cpp

@@ -1,8 +1,12 @@
 #include "D3D12TestFixture.h"
 
-ComPtr<ID3D12Device> D3D12TestFixture::mDevice;
-
 void D3D12TestFixture::SetUpTestSuite() {
+}
+
+void D3D12TestFixture::TearDownTestSuite() {
+}
+
+void D3D12TestFixture::SetUp() {
     HRESULT hr = D3D12CreateDevice(
         nullptr,
         D3D_FEATURE_LEVEL_12_0,
@@ -13,22 +17,11 @@ void D3D12TestFixture::SetUpTestSuite() {
         GTEST_SKIP() << "Failed to create D3D12 device";
         return;
     }
-}
-
-void D3D12TestFixture::TearDownTestSuite() {
-    mDevice.Reset();
-}
-
-void D3D12TestFixture::SetUp() {
-    if (!mDevice) {
-        GTEST_SKIP() << "D3D12 device not available";
-        return;
-    }
     
     D3D12_COMMAND_QUEUE_DESC queueDesc = {};
     queueDesc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
     
-    HRESULT hr = mDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&mCommandQueue));
+    hr = mDevice->CreateCommandQueue(&queueDesc, IID_PPV_ARGS(&mCommandQueue));
     if (FAILED(hr)) {
         GTEST_SKIP() << "Failed to create command queue";
         return;
@@ -54,6 +47,7 @@ void D3D12TestFixture::TearDown() {
     mCommandList.Reset();
     mCommandAllocator.Reset();
     mCommandQueue.Reset();
+    mDevice.Reset();
 }
 
 void D3D12TestFixture::WaitForGPU() {

tests/RHI/D3D12/fixtures/D3D12TestFixture.h

@@ -29,7 +29,7 @@ protected:
     void WaitForGPU();
 
 private:
-    static ComPtr<ID3D12Device> mDevice;
+    ComPtr<ID3D12Device> mDevice;
     ComPtr<ID3D12CommandQueue> mCommandQueue;
     ComPtr<ID3D12CommandAllocator> mCommandAllocator;
     ComPtr<ID3D12GraphicsCommandList> mCommandList;