v2026

- Add sl-2026: screen-aware version with conditional sweep
- Detect existing text on terminal and sweep only when the train reaches it
- Enter from beyond the right edge to preserve right-side text
- Support iTerm2 and Apple Terminal screen capture
- Add -a option for full-screen sweep
- Add -h/--help and --version options
- Add man page (sl.1)
- Add shell script wrapper for version dispatch
- Rename sl.c to sl-1985.c