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/oncancel.md

@@ -0,0 +1,38 @@
+# ITask::OnCancel
+
+```cpp
+virtual void OnCancel()
+```
+
+任务取消回调。可在派生类中重写此方法，以在任务被取消时执行清理操作。
+
+**参数：** 无
+
+**返回：** 无
+
+**复杂度：** 取决于具体实现
+
+**示例：**
+
+```cpp
+class NetworkTask : public ITask {
+public:
+    void Execute() override {
+        for (int i = 0; i < 100; ++i) {
+            if (GetStatus() == TaskStatus::Canceled) {
+                return;
+            }
+            SendPacket(i);
+        }
+    }
+    
+    void OnCancel() override {
+        CloseConnection();
+        printf("Network task canceled\n");
+    }
+};
+```
+
+## 相关文档
+
+- [ITask 总览](task.md) - 返回类总览