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/getloader.md

@@ -0,0 +1,27 @@
+# ResourceManager::GetLoader
+
+```cpp
+IResourceLoader* GetLoader(ResourceType type) const
+```
+
+获取指定类型的资源加载器。
+
+**参数：**
+- `type` - 资源类型
+
+**返回：** 对应的加载器指针，未找到则返回 `nullptr`
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+IResourceLoader* texLoader = ResourceManager::Get().GetLoader(ResourceType::Texture);
+if (texLoader) {
+    auto extensions = texLoader->GetSupportedExtensions();
+}
+```
+
+## 相关文档
+
+- [ResourceManager 总览](resourcemanager.md) - 返回类总览