Add a skill that lets a running nanobot agent create new bot instances
through a helper script. The agent collects instance name, channel type,
and optional model from the user, then runs the script which:
- Calls nanobot onboard to create config + workspace skeleton
- Enables the target channel and sets workspace/model in config
- Auto-assigns gateway/API ports if defaults are occupied
- Validates config via Pydantic before saving
- Reports required fields the user needs to fill in (e.g. bot token)