add split-second-stopwatch

[BNAndras]

No description provided.

[BNAndras]

/format

[github-actions]

The "Format code" action has started running.

[github-actions]

The "Format code" action has finished running.

[github-actions]

For security reasons, /format does not trigger CI builds when the PR has been submitted from a fork. If checks were not passing due to code format, trigger a build to make the required checks pass, through one of the following ways:

• Push an empty commit to this branch: git commit --allow-empty -m "Trigger builds".
• Close and reopen the PR.
• Push a regular commit to this branch.

[BNAndras]

This exercise might be more interesting when https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal/Duration becomes more widespread. The duration as a string feels a bit meh.