fix: calculate box width without escape sequence chars

[yongqi14]

resolves #316

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 29.39%. Comparing base (24c98ce) to head (6d9f0c7).
Report is 40 commits behind head on main.

Files with missing lines	Patch %	Lines
src/utils/box.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #336       +/-   ##
===========================================
- Coverage   61.08%   29.39%   -31.70%     
===========================================
  Files          13       42       +29     
  Lines        1380     1640      +260     
  Branches       58       87       +29     
===========================================
- Hits          843      482      -361     
- Misses        537     1131      +594     
- Partials        0       27       +27     

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