test: Add RHI integration tests and update unit tests

- Add CommandQueue unit tests for WaitForIdle and synchronization
- Add SwapChain unit tests for Present and buffer operations
- Add Texture unit tests for various texture types and mipmaps
- Fix RHIIntegrationFixture with proper logging and debug output
- Update minimal integration test with RHI abstraction layer
- Add GT reference image for minimal test
- Update TEST_SPEC.md documentation

tests/RHI/integration/minimal/CMakeLists.txt

@@ -37,6 +37,7 @@ target_compile_definitions(rhi_integration_minimal PRIVATE
     UNICODE
     _UNICODE
     XCENGINE_SUPPORT_OPENGL
+    XCENGINE_SUPPORT_D3D12
 )
 
 add_custom_command(TARGET rhi_integration_minimal POST_BUILD