refactor: reorganize docs into plan/ and add skills/

docs/api/rhi/opengl/opengl-vertex-array.md

@@ -0,0 +1,88 @@
+# OpenGLVertexArray
+
+OpenGL 顶点数组对象 (VAO) 封装。
+
+## 头文件
+
+```cpp
+#include <XCEngine/RHI/OpenGL/OpenGLVertexArray.h>
+```
+
+## VertexAttribute
+
+```cpp
+struct VertexAttribute {
+    unsigned int index;    // 属性索引 (layout location)
+    int count;             // 组件数量 (1-4)
+    unsigned int type;     // GL 类型 (GL_FLOAT, etc.)
+    bool normalized;       // 是否归一化
+    size_t stride;         // 顶点步长
+    size_t offset;         // 属性偏移
+};
+```
+
+## 公共成员函数
+
+#### `OpenGLVertexArray()`
+
+#### `~OpenGLVertexArray()`
+
+#### `bool Initialize()`
+
+#### `void AddVertexBuffer(unsigned int buffer, const VertexAttribute& attribute)`
+
+#### `void SetIndexBuffer(unsigned int buffer, unsigned int type)`
+
+#### `void Shutdown()`
+
+#### `void Bind() const`
+
+#### `void Unbind() const`
+
+#### `unsigned int GetID() const`
+
+#### `unsigned int GetIndexBuffer() const`
+
+#### `unsigned int GetIndexCount() const`
+
+## 内部成员
+
+| 成员 | 类型 | 描述 |
+|------|------|------|
+| `m_vao` | `unsigned int` | GL VAO ID |
+| `m_indexBuffer` | `unsigned int` | 索引缓冲区 |
+| `m_indexCount` | `unsigned int` | 索引数量 |
+| `m_vertexBufferCount` | `int` | 顶点缓冲区数量 |
+
+## 使用示例
+
+```cpp
+OpenGLVertexArray vao;
+vao.Initialize();
+
+// Position attribute
+VertexAttribute pos;
+pos.index = 0;
+pos.count = 3;
+pos.type = GL_FLOAT;
+pos.normalized = false;
+pos.stride = sizeof(Vertex);
+pos.offset = 0;
+vao.AddVertexBuffer(vb.GetID(), pos);
+
+// UV attribute
+VertexAttribute uv;
+uv.index = 1;
+uv.count = 2;
+uv.type = GL_FLOAT;
+uv.normalized = false;
+uv.stride = sizeof(Vertex);
+uv.offset = sizeof(float) * 3;
+vao.AddVertexBuffer(vb.GetID(), uv);
+
+// Index buffer
+vao.SetIndexBuffer(ib.GetID(), GL_UNSIGNED_SHORT);
+
+vao.Bind();
+glDrawElements(GL_TRIANGLES, vao.GetIndexCount(), GL_UNSIGNED_SHORT, 0);
+```