v2.1.0

release: bump version to v2.1.0

- Update Cargo.toml version to 2.1.0
- Update package.json version to 2.1.0
- Add comprehensive changelog entry for wizard redesign
- Create new Homebrew formula for anvs
- Prepare for v2.1.0 release with wizard improvements

Features:
- Quick mode wizard (< 30s setup)
- Advanced mode with full customization
- Visual timeline progress indicators
- Smart auto-detection with inline display
- Modern CLI experience inspired by Vite/ShadCN

Breaking changes:
- Default anvs init now uses quick mode (was verbose wizard)