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/containers/hashmap/iterator.md

@@ -0,0 +1,34 @@
+# HashMap::begin / end
+
+```cpp
+Iterator begin();
+Iterator end();
+ConstIterator begin() const;
+ConstIterator end() const;
+```
+
+获取哈希表的迭代器。迭代器遍历所有桶中的元素。
+
+**参数：** 无
+
+**返回：** 返回指向第一个元素和末尾（最后一个元素之后）位置的迭代器。
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+XCEngine::Containers::HashMap<int, const char*> map;
+map.Insert(1, "one");
+map.Insert(2, "two");
+map.Insert(3, "three");
+
+for (auto it = map.begin(); it != map.end(); ++it) {
+    std::cout << it->first << " -> " << it->second << std::endl;
+}
+// 输出顺序不确定，取决于哈希桶的内部布局
+```
+
+## 相关文档
+
+- [HashMap 总览](hashmap.md) - 返回类总览