docs: update math API docs

docs/api/math/obb/contains.md

@@ -0,0 +1,35 @@
+# OBB::Contains
+
+```cpp
+bool Contains(const Vector3& point) const;
+```
+
+检测给定点是否位于 OBB 包围盒内部。通过将点变换到局部坐标系，然后检查其坐标分量是否在半长向量范围内。
+
+**参数：**
+- `point` - 待检测的三维点
+
+**返回：** 点在包围盒内返回 `true`，否则返回 `false`
+
+**异常：** 无
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include "AABB.h"
+#include "Vector3.h"
+
+using namespace XCEngine::Math;
+
+OBB obb(Vector3(0.0f, 0.0f, 0.0f), Vector3(1.0f, 0.5f, 1.0f));
+
+Vector3 insidePoint(0.0f, 0.0f, 0.0f);
+Vector3 outsidePoint(2.0f, 0.0f, 0.0f);
+
+bool isInside = obb.Contains(insidePoint);
+bool isOutside = obb.Contains(outsidePoint);
+```