Remove duplicates from `tui/cool_tips.txt` & add a CI that checks the file

[koibtw]

Description

Removed duplicates from tui/cool_tips.txt & added a CI that checks the file for duplicate entries.

Testing

Tested, works.

Impact

The CI will work only on PRs or pushes that modify the file.

Checklist

• [x] My code adheres to the coding and style guidelines of the project.
• [x] I have performed a self-review of my own code.
• [x] My changes generate no errors/warnings/merge conflicts.