- Add m_boundRenderTargets and m_boundDepthStencil members to D3D12CommandList
- SetRenderTargetsHandle now saves bound RTV handles for later clear operations
- ClearRenderTargetView(ID3D12Resource*, ...) clears all bound render targets
- Reset() clears bound targets list
- Follows D3D12 best practice: RTV is bound via OMSetRenderTargets, then cleared
- Add default value handling for sampleCount, mipLevels, depth in CreateTexture
- Add RTV descriptor heap to D3D12CommandList for future ClearRenderTarget implementation
- ClearRenderTarget remains stub (requires full D3D12 render pipeline state)
- Add DepthStencilState and BlendState structs to RHICommandList
- Add SetPrimitiveTopology, SetDepthStencilState, SetStencilRef,
SetBlendState, SetBlendFactor virtual methods
- Implement new methods in OpenGL backend with full state control
- Implement stub methods in D3D12 backend (states controlled via PSO)
