Add collection CRUD commands

[felix-exon]

Summary

• add a new collection command group with get, list, create, update, and delete
• wire collection dispatch/help/dry-run mappings into the root CLI
• extend output formatting to display collection records cleanly in human and quiet modes
• update README and package description for collection support
• add tests covering collection command routing and payload mapping

Validation

• bun test
• bun run typecheck
• bun run build