Homework submit version

课程附加题作业提交时的版本。

##功能：

• 横竖屏切换科学/普通计算器
• 暗色模式和亮色模式切换
• 历史记录显示（显示运算过程和结构）
• 历史记录结构调用（点击某一条历史记录后），返回输入选择的结果
• 历史记录清空
  注意：历史记录没有写入文件，为暂存文件，删除后台后消失。

Version Submitted for Additional Course Assignment

Features:

• Switch between scientific/standard calculators in landscape/portrait mode
• Toggle between dark mode and light mode
• Display of history records (showing the calculation process and results)
• Recall history records (clicking on a specific history record will return its result for input)
• Clear history records
  Note: History records are stored temporarily and are not written to files. They will disappear after the app is closed.