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/debug/loglevel/logleveltostring.md

@@ -0,0 +1,28 @@
+# LogLevelToString
+
+```cpp
+const char* LogLevelToString(LogLevel level)
+```
+
+将 `LogLevel` 枚举值转换为可读字符串。
+
+**参数：**
+- `level` - 日志级别
+
+**返回：** 对应级别的字符串（"VERBOSE", "DEBUG", "INFO", "WARNING", "ERROR", "FATAL"）
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include <XCEngine/Debug/LogLevel.h>
+
+XCEngine::Debug::LogLevel level = XCEngine::Debug::LogLevel::Error;
+const char* str = XCEngine::Debug::LogLevelToString(level);
+// str == "ERROR"
+```
+
+## 相关文档
+
+- [LogLevel 总览](loglevel.md) - 返回类总览