fix: prevent spinner wrapping in narrow terminals

[maxbeizer]

Summary

• measure the terminal width for every spinner frame so live resizes are respected
• truncate progress messages by display-cell width with a safety column to prevent automatic wrapping
• preserve existing behavior when terminal size is unavailable and keep non-terminal output silent

Testing

• make ci

Fixes #40

[maxbeizer]

Reviewed the terminal-width spinner changes. The review identified and the branch now addresses MSYS/Cygwin width detection, locale-dependent display widths, and the East Asian ellipsis boundary. Final pass found no remaining high-confidence issues.

[maxbeizer]

Reviewed the terminal-width spinner changes. The review identified and the branch now addresses MSYS/Cygwin width detection, locale-dependent display widths, and the East Asian ellipsis boundary. Final pass found no remaining high-confidence issues.