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/h/half-pi.md

@@ -0,0 +1,19 @@
+# Math::HALF_PI
+
+```cpp
+constexpr float HALF_PI = 1.57079632679489661923f;
+```
+
+`HALF_PI` 是圆周率除以 2，即 90 度对应的弧度值，约为 1.57079632679489661923。该常量常用于角度与弧度的转换、四分之一圆周计算等场景。
+
+**示例：**
+
+```cpp
+#include <XCEngine/Math/Math.h>
+
+float ninetyDegreesRadians = Math::HALF_PI;
+```
+
+## 相关文档
+
+- [Math 总览](h.md) - 返回 Math 概览