Add Phase 2 tests for CommandQueue, CommandAllocator, CommandList

- CommandAllocator: Reset, MultipleReset, DifferentTypes
- CommandList: Close, GetDesc
- CommandQueue: GetTimestampFrequency, ExecuteCommandLists
- Note: Some tests fail after ExecuteCommandLists due to GPU state

tests/RHI/D3D12/test_command_queue.cpp

@@ -1,5 +1,27 @@
 #include "fixtures/D3D12TestFixture.h"
 
 TEST_F(D3D12TestFixture, CommandQueue_Placeholder) {
-    ASSERT_TRUE(true);
+    ASSERT_NE(GetCommandQueue(), nullptr);
+}
+
+TEST_F(D3D12TestFixture, CommandQueue_GetTimestampFrequency) {
+    D3D12_COMMAND_QUEUE_DESC desc = {};
+    desc.Type = D3D12_COMMAND_LIST_TYPE_DIRECT;
+    
+    ComPtr<ID3D12CommandQueue> queue;
+    HRESULT hr = GetDevice()->CreateCommandQueue(&desc, IID_PPV_ARGS(&queue));
+    ASSERT_HRESULT_SUCCEEDED(hr);
+    
+    UINT64 frequency;
+    hr = queue->GetTimestampFrequency(&frequency);
+    ASSERT_HRESULT_SUCCEEDED(hr);
+    EXPECT_GT(frequency, 0);
+}
+
+TEST_F(D3D12TestFixture, CommandQueue_ExecuteCommandLists_Empty) {
+    GetCommandList()->Reset(GetCommandAllocator(), nullptr);
+    ID3D12CommandList* commandLists[] = { GetCommandList() };
+    GetCommandQueue()->ExecuteCommandLists(1, commandLists);
+    GetCommandList()->Close();
+    WaitForGPU();
 }