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/debug/ilogsink/flush.md

@@ -0,0 +1,32 @@
+# ILogSink::Flush
+
+```cpp
+virtual void Flush() = 0
+```
+
+刷新输出缓冲区，确保所有待写入的日志数据已实际写入目标介质。对于文件类 Sink，应调用底层文件系统的 flush；对于网络类 Sink，应发送缓冲区中的数据。
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+class BufferedLogSink : public XCEngine::Debug::ILogSink {
+private:
+    std::string m_buffer;
+public:
+    void Log(const XCEngine::Debug::LogEntry& entry) override {
+        m_buffer += entry.message.CStr();
+        m_buffer += "\n";
+    }
+    void Flush() override {
+        // 将缓冲区数据写入目标
+        writeToDestination(m_buffer);
+        m_buffer.clear();
+    }
+};
+```
+
+## 相关文档
+
+- [ILogSink 总览](ilogsink.md) - 返回类总览