feat: 添加独立的输入系统和平台抽象层

- 新增 Platform 模块：PlatformTypes.h, Window.h, WindowsWindow
- 新增 Input 模块：InputTypes, InputEvent, InputAxis, InputModule, InputManager
- 新增 WindowsInputModule 处理 Win32 消息转换
- 将 RHI 集成测试从 render_model 迁移到 sphere
- 更新 CMakeLists.txt 添加 Platform 和 Input 模块

tests/RHI/D3D12/integration/sphere/Res/Shader/sphere.hlsl

@@ -0,0 +1,24 @@
+struct Vertex {
+    float4 pos : POSITION;
+    float4 texcoord : TEXCOORD0;
+};
+
+struct VSOut {
+    float4 pos : SV_POSITION;
+    float4 texcoord : TEXCOORD0;
+};
+
+cbuffer MatrixBuffer : register(b0) {
+    float4x4 gMVP;
+};
+
+VSOut MainVS(Vertex v) {
+    VSOut o;
+    o.pos = mul(gMVP, v.pos);
+    o.texcoord = v.texcoord;
+    return o;
+}
+
+float4 MainPS(VSOut i) : SV_TARGET {
+    return float4(1.0f, 0.0f, 0.0f, 1.0f);
+}