refactor: convert mac-optimizer from raw skill to proper plugin

Restructured 92-mac-optimizer from a CLAUDE.md-based skill into a full
Claude Code plugin with .claude-plugin/plugin.json, 6 slash commands
(/mac-doctor, /mac-packages, /mac-environment, /mac-security,
/mac-cleanup, /mac-resources), and auto-trigger SKILL.md.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

custom-skills/92-mac-optimizer/skills/mac-optimizer/references/cleanup-targets.md

@@ -0,0 +1,74 @@
+# Cleanup Targets Reference
+
+## Risk Ratings
+
+| Risk | Meaning |
+|---|---|
+| Safe | Can be deleted without consequence; regenerated automatically |
+| Moderate | Review before deleting; may lose useful data |
+| Risky | May break applications; requires careful inspection |
+| Info only | Report size but do not offer deletion |
+
+## Target Details
+
+### User Logs (Safe)
+- **Path**: `~/Library/Logs/`
+- **Cleanup target**: `user-logs`
+- **Notes**: Application crash reports and debug logs. Regenerated as needed.
+
+### System Logs (Moderate, requires sudo)
+- **Path**: `/var/log/`
+- **Cleanup target**: not available via cleanup_execute.sh (requires sudo)
+- **Notes**: System-level logs. Only clean old/rotated files. Active logs should not be deleted.
+
+### User Caches (Safe, per-app)
+- **Path**: `~/Library/Caches/`
+- **Cleanup target**: `user-caches`
+- **Notes**: App caches regenerated on next use. Some apps may need to re-download data. Browser caches can be large.
+
+### Homebrew Cache (Safe)
+- **Path**: `$(brew --cache)` (typically `~/Library/Caches/Homebrew/`)
+- **Cleanup target**: `brew-cache`
+- **Notes**: Downloaded bottles and source archives. `brew cleanup` handles this properly.
+
+### npm Cache (Safe)
+- **Path**: `~/.npm/_cacache/`
+- **Cleanup target**: `npm-cache`
+- **Notes**: Package download cache. `npm cache clean --force` is the proper way to clear.
+
+### pip Cache (Safe)
+- **Path**: `~/Library/Caches/pip/`
+- **Cleanup target**: `pip-cache`
+- **Notes**: Downloaded wheel/sdist cache. `pip cache purge` is the proper way to clear.
+
+### Xcode DerivedData (Safe)
+- **Path**: `~/Library/Developer/Xcode/DerivedData/`
+- **Cleanup target**: `xcode-derived`
+- **Notes**: Build artifacts and indexes. Rebuilt on next Xcode build. Can grow very large.
+
+### Xcode Archives (Moderate)
+- **Path**: `~/Library/Developer/Xcode/Archives/`
+- **Cleanup target**: `xcode-archives`
+- **Notes**: App Store submission archives. May be needed for symbolication of crash reports. Review before deleting.
+
+### iOS DeviceSupport (Safe)
+- **Path**: `~/Library/Developer/Xcode/iOS DeviceSupport/`
+- **Cleanup target**: `ios-support`
+- **Notes**: Debug symbols for connected iOS devices. Re-downloaded when device connects again.
+
+### Docker (Moderate)
+- **Cleanup target**: `docker`
+- **Notes**: Uses `docker system prune -f`. Removes stopped containers, unused networks, dangling images. Does NOT remove named volumes. Never delete Docker's filesystem directly.
+
+### Trash (Safe)
+- **Path**: `~/.Trash/`
+- **Cleanup target**: `trash`
+- **Notes**: Items in Trash. User has already "deleted" these.
+
+### Old Downloads (Info only)
+- **Path**: `~/Downloads/` (files >90 days old)
+- **Notes**: Report only. User should review manually. Never auto-delete downloads.
+
+### Application Support Remnants (Risky)
+- **Path**: `~/Library/Application Support/` orphaned directories
+- **Notes**: Report only. Directories from uninstalled apps. Difficult to determine automatically which are truly orphaned. Manual review required.