feat(tui): show skills used during a session

[guidobuilds]

Issue for this PR

Closes #14201

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Added a Skills section to the session sidebar that tracks and displays all skills invoked during the session. When more than 2 skills are used, the section collapses and can be expanded by clicking.

How did you verify your code works?

Ran the TUI locally, triggered a few skills, and confirmed they show up in the sidebar correctly. Tested with 0, 1, 2, and more than 2 skills (collapse behavior). Tested in macOS only.

Screenshots / recordings

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate Found

PR #6154: feat: show skills in status and sidebar
#6154

This PR appears to be directly related - it also implements showing skills in the sidebar. You may want to verify if this is an older closed/merged PR that addressed similar functionality, or if there's overlap in scope.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍

[ariane-emory]

For the many users who prefer not to use skills, this sidebar entry will just be noise consuming valuable vertical space.

Either:

• it ought not display if no skills are loaded
• or there ought to be a way to disable it

Vertical sidebar space is valuable and ought not be wasted lightly.

[github-actions]

Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.