tty/monopam: improve progress bar and optimize push
Progress bar improvements:
- Fix terminal width detection to reject invalid values (COLUMNS=0)
- Add cursor hiding during updates for cleaner display
- Use time-based spinner (10 fps) instead of update-based
- Add \027[K (clear to end of line) for clean overwrites
- Add Plain style for testing without colors/spinner
- Add debug mode via TTY_PROGRESS_DEBUG env var
Monopam push optimizations:
- Skip repos that are already in sync (uses status info)
- Increase remote push parallelism from 2 to 8 fibers
- Early exit when nothing to push