feat: 实现D3D12 RHI抽象层，修复PSO创建问题

- 添加RHI接口定义(IRHIDevice, ICommandList, IResource等)
- 实现D3D12Device, D3D12CommandList, D3D12PipelineState等
- 修复RootSignature参数数量(3->4)与HelloEarth一致
- 修复DSV格式设置(Unknown->D24_UNorm_S8_UInt)
- 添加Geometry Shader编译
- 创建XCEngineDemo项目验证RHI功能

MVS/HelloEarth/CMakeLists.txt

@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 3.15)
+
+project(HelloEarth)
+
+add_executable(HelloEarth
+    WIN32
+    main.cpp
+    BattleFireDirect.cpp
+    StaticMeshComponent.cpp
+    Utils.cpp
+    stbi/stb_image.cpp
+)
+
+target_compile_definitions(HelloEarth PRIVATE
+    UNICODE
+    _UNICODE
+)
+
+target_include_directories(HelloEarth PRIVATE
+    ${CMAKE_SOURCE_DIR}/mvs/HelloEarth
+    ${CMAKE_SOURCE_DIR}/mvs/HelloEarth/stbi
+)
+
+target_link_libraries(HelloEarth PRIVATE
+    d3d12
+    dxgi
+    d3dcompiler
+    winmm
+)