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/core/event/begin.md

@@ -0,0 +1,37 @@
+# Event::begin
+
+```cpp
+Iterator begin();
+```
+
+获取开始迭代器。
+
+**描述**
+
+返回订阅列表的开始迭代器，用于范围for循环遍历所有订阅的回调。
+
+**返回：** `Iterator` - 指向第一个监听器的迭代器（等价于 `std::vector<Listener>::iterator`）
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+#include <XCEngine/Core/Event.h>
+
+using namespace XCEngine::Core;
+
+Event<int> event;
+event.Subscribe([](int v) { printf("Callback 1: %d\n", v); });
+event.Subscribe([](int v) { printf("Callback 2: %d\n", v); });
+
+// 遍历所有订阅
+for (auto& [id, callback] : event) {
+    callback(100);
+}
+```
+
+## 相关文档
+
+- [Event 总览](event.md) - 返回类总览
+- [end](end.md) - 获取结束迭代器