比赛题目页面里左侧栏加入题目序号列表

[boomzero]

What does this PR aim to accomplish?:

比赛题目页面里左侧栏加入题目序号列表

How does this PR accomplish the above?:

This PR introduces a new "Problem Switcher" feature for contest problem pages. This feature adds a floating sidebar to the left of the screen, allowing users to quickly switch between problems in a contest.

Changelog:

• New Feature:
  • Adds a floating sidebar on contest problem pages (problem.php with a cid).
  • The sidebar displays a list of buttons representing the problems in the contest.
  • The buttons are labeled "A", "B", "C", etc., and will use lowercase letters if there are more than 26 problems.
  • The current problem is highlighted in the sidebar.
  • The sidebar is scrollable if the number of problems exceeds the screen height.
• Settings:
  • The "Problem Switcher" feature can be enabled or disabled in the script's settings menu under the "Beautify" section.
• UI/UX:
  • The sidebar is designed to be unobtrusive and easy to use.
  • It adapts to the website's dark mode setting.

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