fix: improve doc link navigation and tree display

- Fix link resolution with proper relative/absolute path handling
- Improve link styling with underline decoration
- Hide leaf nodes from tree, only show directories
- Fix log file path for packaged app

docs/api/math/matrix4/identity.md

@@ -0,0 +1,17 @@
+# Matrix4::Identity
+
+```cpp
+static Matrix4 Identity()
+```
+
+返回 4x4 单位矩阵。
+
+**返回：** `Matrix4` - 单位矩阵
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+Matrix4 identity = Matrix4::Identity();
+```