discord-nibiru: modernize discord bot tooling and moderation flows

[Unique-Divine]

Summary

• Cleaned up legacy tooling: removed the unused Python automation and legacy
  eslint config, pared package.json down to Bun + TypeScript, and tightened
  .gitignore to cover the new .tmp/ scratch directory.
• Refreshed docs: rewrote README.md with Bun-based setup instructions,
  clarified command coverage, and added plan.md to track remaining workstreams
  and future ideas.
• Hardened moderation commands: centralized JSON dumps into .tmp/, enriched
  grant-roles with dry-run support and structured logging, and updated utilities
  to timestamp outputs while logging every moderation action.

Testing

• Manual only; no automated tests were run.