nodara CLI v2.0

The old nodara CLI was written in Node and had a ~700ms cold start. It's now a single-file Rust binary that starts in about 22ms.

The biggest UX change is auth: nodara login now uses OAuth device flow, so there's no more copy-pasting API tokens.

Migration is a one-liner: curl -fsSL nodara.host/cli | sh — it detects and removes the old install.