Add ./mcp-menu.sh for safe, read-only onboarding and workflow prompt
discovery. Includes root checkout health, role prompts, onboarding
checklist, Proxmox placeholders, and run-tests fallback. Document in
docs/mcp-menu.md with hermetic tests.
Closes#478.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
