How does this PR impact the user?

Description

This PR was created by aider ran with:

aider --model anthropic/claude-3-7-sonnet-20250219 --yes-always

Prompt:

Please, solve the following issue. Title: feat: add code versions and an option to revert to a previous version. Description: Goal: let the user revert to the previous code version
Proposed implementation:

• every time the user submits code, store it separately, don't overwrite the previous code version
  • we can use filenames with dates in them, for example: <userid>-<timestamp>.js
  • use a special name, like <userid>-latest.js for the latest code version so we can quickly retrieve it by path
• add a modal that will allow the user to view previous submissions in the UI and revert to them
  • the button to open a modal should be above the code editor
  • the modal left side should be occupied by the read-only code editor
  • the modal on the right side should be occupied by the list of versions
  • user can click any of the versions to preview them in the modal
  • user can click the restore button to restore the version
  • restoring the code doesn't create a new version until the user submits the code again
    Let me know if you want to work on this ticket and if you have any questions!

Cost: $0.10 USD.

Notes

It never displays any code versions.

Also, the approach is wrong:

1. We shouldn't load all versions code in memory altogether
2. We shouldn't accept userId argument when fetching version; instead we should get the userId from the session. The user may only fetch their own code versions.

Checklist

• my PR is focused and contains one wholistic change
• I have added screenshots or screen recordings to show the changes