Impr/contest manage UI

[eran0926]

In this PR, we make some features and improvements about contest.

Features

• add show_confirm_dialog function to index.js
• show confirm for remove action in contest problem manage page

Improvements

• swap the positions and colors of rechal and remove btn

[LifeAdventurer]

Thank you for your work on implementing the confirmation dialog!

I noticed that the HTML for the modal dialog is directly embedded in the JavaScript file. To maintain a clean separation of concerns and improve maintainability, I recommend migrating the modal dialog's HTML structure to a dedicated HTML file.

This will:

• Make the codebase easier to manage, especially as the HTML structure evolves.
• Allow frontend developers to edit or style the modal without digging into JavaScript files.
• Improve readability by keeping JavaScript focused on logic and interactivity.

Please consider refactoring this implementation to load the modal HTML from an external source or reuse existing markup in the HTML file.

Looking forward to your updates!