Add env auth, MCP hints, and workflow validation

✨ Features
- [auth]: add LUNE_ACCESS_TOKEN env var support as keyring alternative
- [mcp]: add OpenWorldHint and Title annotations to all tools
- [mcp]: add LUNE_ACCESS_TOKEN fallback for containerized environments
- [task]: add workflow-aware status validation with contextual error
  messages
- [area]: add hint when goal list is truncated

🐛 Bug Fixes
- [cli]: pass context to done shortcut fixing nil Context errors

♻️ Code Refactoring
- [completion]: use go-lunatask All*() functions for completions

📚 Documentation
- [docs]: update cross-promo links
- [cli]: add completed to status flag help

🔧 Build System
- [deps]: bump go-lunatask to v0.1.0
- [deps]: bump golang.org/x/crypto, oauth2, sys, text and others
-----BEGIN SSH SIGNATURE-----
U1NIU0lHAAAAAQAAAEoAAAAac2stc3NoLWVkMjU1MTlAb3BlbnNzaC5jb20AAAAgzEkAhr
f0dc6ZiSJXHc/mDhl7rRRGcNCSuENi7R/pfKkAAAAEc3NoOgAAAANnaXQAAAAAAAAABnNo
YTUxMgAAAGcAAAAac2stc3NoLWVkMjU1MTlAb3BlbnNzaC5jb20AAABA6chwsuUS6bkP7f
+ltV2rWkzAxKRifDH4dNn1FmlrKC3ptYvKQAtUm67NIPkKE3k5yzak7uH2Wm+JAescaZzL
BQEAALa8
-----END SSH SIGNATURE-----