Adds SessionStart hook that checks npm in background, caches result.
Statusline shows "⬆ /gsd:update │" when update available.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
- Install statusline.sh to {claudeDir}/hooks/
- Configure statusLine in settings.json automatically
- Skip if statusline already exists (non-interactive)
- Prompt to keep/replace in interactive mode
- Add --force-statusline flag to override
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>