Add a guided onboarding wizard for Buddy setup

[owenqwenstarsky]

Summary

• add a buddy onboard flow with a step-by-step TUI wizard and final review before saving
• add an initial server setup step for local vs remote Buddy connections, including local token detection and a remote alpha warning
• update CLI auth handling so local connections use the standard local token and remote connections store their own auth key
• add onboarding coverage in tests and document the new setup flow in the README

Testing

• npm test
• npm run check