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/resources/iloader/loadasync.md

@@ -0,0 +1,34 @@
+# IResourceLoader::LoadAsync
+
+```cpp
+void LoadAsync(const Containers::String& path, const ImportSettings* settings,
+               std::function<void(LoadResult)> callback)
+```
+
+异步加载资源。默认实现直接调用同步 `Load` 方法并在当前线程执行回调。子类可重写以实现真正的多线程异步加载。
+
+**参数：**
+- `path` - 资源路径
+- `settings` - 导入设置（可为 nullptr）
+- `callback` - 加载完成回调函数
+
+**返回：** 无
+
+**复杂度：** O(n)
+
+**示例：**
+
+```cpp
+void AsyncTextureLoader::LoadAsync(const Containers::String& path,
+                                  const ImportSettings* settings,
+                                  std::function<void(LoadResult)> callback) {
+    std::thread([this, path, settings, callback]() {
+        LoadResult result = Load(path, settings);
+        callback(result);  // 回调可在工作线程执行
+    }).detach();
+}
+```
+
+## 相关文档
+
+- [IResourceLoader 总览](iloader.md) - 返回类总览