fix: use full argument in NoSuchOption for short options

[RogueTex]

Summary

Fixes #2779 - when a multi-character short option like -dbgwrong is passed and not found, the error message previously showed only the first character (e.g., No such option: -d) instead of the full argument.

Root cause: _match_short_opt iterated over single characters and raised NoSuchOption(opt) where opt was the single-char option string. The arg parameter (the full original argument) was available but unused in the error.

Fix: Pass arg instead of opt to NoSuchOption, so users see the full string they typed.

Before:

Error: No such option: -d

After:

Error: No such option: -dbgwrong

Closes #2779