- Replace PAPERCLIP art with NEXUS art in server/src/startup-banner.ts
- Replace full cli/src/utils/banner.ts with NEXUS art and updated tagline
- Rename printPaperclipCliBanner to printNexusCliBanner
- Update tagline to 'Open-source orchestration for your agents'
- Update all 5 CLI command callers: onboard, configure, db-backup, worktree, doctor
- Satisfies BRND-02