- Add assert() bounds check to GetBackBuffer() to catch invalid indices
- Include <cassert> in D3D12SwapChain.cpp
- Update test_swap_chain.cpp to use reference return type
- Mark InvalidIndex test as DISABLED (assert aborts on invalid index)
- Update get-back-buffer.md documentation
- Add D3D12Screenshot::Capture(D3D12Device&, D3D12CommandQueue&, D3D12Texture&, const char*) wrapper overload
- Update minimal integration test to use encapsulated APIs
- Add DescriptorHeap wrapper unit tests
- Document minimal GetBuffer native call as known limitation in TEST_SPEC.md
- Move test_*.cpp and fixtures/ to tests/RHI/D3D12/unit/
- Create unit/CMakeLists.txt with proper test configuration
- Simplify parent CMakeLists.txt to use add_subdirectory
- Integration tests remain in integration/ folder