Enhance Problem Customization by Restructuring Tdoc Schema

[bhscer]

!!! Still need careful check if any logic is wrong or some changes is missing !!!

Idea is from: #1015

Currently call contest.add or contest.edit without data.problems will automatically build it, so that maybe friendly for plugin users.
Current ContestHandlers will also update pid,score, balloon.

Summary by CodeRabbit

• New Features

  • Introduced a unified contest problem configuration system, allowing custom labels, scores, and balloon colors for each problem.
  • Added a drag-and-drop editor for contest and homework problems with structured configuration in the UI.
  • Enhanced scoreboard and contest views to display problem labels and scores from the new configuration.
  • Improved localization with new Chinese translations for problem-related fields.

• Bug Fixes

  • Prevented errors in autocomplete when the input value is null or undefined.
  • Ensured problem language lists are only shown when not empty.

• Style

  • Standardized column widths in contest and homework editing tables for a consistent layout.

• Documentation

  • Updated templates and macros to consistently use the new problem configuration for labels, scores, and balloon colors.

• Chores

  • Added a migration script to transition existing contests to the new problem configuration format.