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/unloadunused.md

@@ -0,0 +1,26 @@
+# ResourceManager::UnloadUnused
+
+```cpp
+void UnloadUnused()
+```
+
+卸载所有无引用的资源。遍历资源缓存，将引用计数为零的资源全部释放。常在场景切换或内存紧张时调用。
+
+**参数：** 无
+
+**返回：** 无
+
+**复杂度：** O(n)
+
+**示例：**
+
+```cpp
+// 切换场景时清理无用资源
+void OnSceneUnload() {
+    ResourceManager::Get().UnloadUnused();
+}
+```
+
+## 相关文档
+
+- [ResourceManager 总览](resourcemanager.md) - 返回类总览