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/resourcemanager/loadasync.md

@@ -0,0 +1,44 @@
+# ResourceManager::LoadAsync
+
+```cpp
+void LoadAsync(const Containers::String& path, ResourceType type,
+               std::function<void(LoadResult)> callback)
+void LoadAsync(const Containers::String& path, ResourceType type,
+               ImportSettings* settings, std::function<void(LoadResult)> callback)
+```
+
+异步加载资源。将加载请求提交到 `AsyncLoader`，在后台工作线程执行加载，完成后在主线程通过回调通知。
+
+**参数：**
+- `path` - 资源路径
+- `type` - 资源类型
+- `settings` - 导入设置（可为 nullptr）
+- `callback` - 加载完成回调
+
+**返回：** 无
+
+**复杂度：** 提交 O(1)，实际加载 O(n)
+
+**示例：**
+
+```cpp
+ResourceManager::Get().LoadAsync("textures/terrain.png", ResourceType::Texture,
+    [](LoadResult result) {
+        if (result.success) {
+            ResourceHandle<Texture> tex(result.resource);
+            printf("Loaded: %s\n", tex->GetPath().CStr());
+        }
+    });
+
+ResourceManager::Get().LoadAsync("models/player.fbx", ResourceType::Mesh,
+    nullptr,
+    [](LoadResult result) {
+        if (result.success) {
+            ResourceHandle<Mesh> mesh(result.resource);
+        }
+    });
+```
+
+## 相关文档
+
+- [ResourceManager 总览](resourcemanager.md) - 返回类总览