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/threading/task-system/get.md

@@ -0,0 +1,26 @@
+# TaskSystem::Get
+
+```cpp
+static TaskSystem& Get()
+```
+
+获取 TaskSystem 单例实例。第一次调用时创建单例。
+
+**参数：** 无
+
+**返回：** `TaskSystem&` - 单例实例的引用
+
+**复杂度：** O(1)
+
+**线程安全：** 线程安全
+
+**示例：**
+
+```cpp
+TaskSystem& system = TaskSystem::Get();
+system.Initialize(config);
+```
+
+## 相关文档
+
+- [TaskSystem 总览](task-system.md) - 返回类总览