use wcwidth

I have some functions to determine the width of a string, but that's not always reliable.
[wcwidth](https://pypi.org/project/wcwidth/) seems like a better alternative

Locate the existing functions that determine string width and inspect how terminal UI sizing uses them. Review the wcwidth package documentation linked in the issue, then replace the unreliable width handling with it and verify that string-width calculations remain correct.

Written by the indexing model from the issue text.