This allows users to install and update gstack through the native Claude Code plugin system:
```
/plugin marketplace add garrytan/gstack
/plugin install gstack@gstack-marketplace
```
- Add `.claude-plugin/` marketplace and plugin manifests
- Move skills into `skills/` directory for plugin auto-discovery
- Use `${CLAUDE_SKILL_DIR}` for portable paths
- Removes (now unneeded) setup script
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Hunter Wittenborn
Garry Tan
morluto