Fixes#363
The update command was hardcoded to use --global flag, which would
convert a local installation to a global one during updates.
Changes:
- Detect install type by checking ./.claude/ first, then ~/.claude/
- Use --local flag when updating a local install
- Use --global flag when updating a global install
- Update cache cleanup path to match install location
- Clarify warning message paths to be relative to install location
- Wipe commands/gsd/ and get-shit-done/ before copying
- Delete only gsd-*.md agents (preserves user agents)
- Add confirmation step to /gsd:update with changelog preview
- Warn users about clean install behavior before updating
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>
