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/containers/string/clear.md

@@ -0,0 +1,39 @@
+# String::Clear
+
+```cpp
+void Clear();
+```
+
+清空字符串内容，将长度设为 0，但不释放已分配的内存。
+
+**参数：** 无
+
+**返回：** 无
+
+**复杂度：** O(1)
+
+**示例：**
+```cpp
+#include "XCEngine/Containers/String.h"
+#include <iostream>
+
+int main() {
+    XCEngine::Containers::String s("Hello World");
+    std::cout << "Before clear - Length: " << s.Length()
+              << ", Capacity: " << s.Capacity() << std::endl;
+    // 输出: Before clear - Length: 11, Capacity: 12
+
+    s.Clear();
+    std::cout << "After clear - Length: " << s.Length()
+              << ", Capacity: " << s.Capacity() << std::endl;
+    // 输出: After clear - Length: 0, Capacity: 12
+    std::cout << "Empty: " << s.Empty() << std::endl;  // 输出: Empty: 1
+
+    return 0;
+}
+```
+
+## 相关文档
+
+- [String 总览](string.md) - 返回类总览
+- [Reserve / Resize](reserve-resize.md) - 内存管理