Display the number of context compressions in the CLI status bar when
compressions > 0, helping users understand conversation compression
pressure during long sessions.
- Wide layout (>=76 cols): shows 'cmp N' between context percent and duration
- Medium layout (52-75 cols): shows 'cmp N' between percent and duration
- Narrow layout (<52 cols): omitted to save space
- Color-coded: dim for 1-4, warn for 5-9, bad for 10+
- Hidden when zero to keep the bar clean for new sessions
Closes#18564
103e11926f