Config `width` was position #3 in the detection chain, overriding all
dynamic detection (ioctl, process tree, stty, etc). This meant the
statusline couldn't adapt to terminal/pane resizes.
Now config `width` serves two roles:
- Max cap on dynamically detected widths (prevents absurd widths)
- Fallback when all dynamic detection methods fail
Also adds:
- ioctl on stderr (works when stdout is piped)
- stdin JSON `terminal_width` field for Claude Code to pass width
- Distinct diagnostic sources: config_cap, config_fallback, stdin_json
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
