add nautilus chain

[aarifkhamdi]

PR-Codex overview

This PR adds support for the Nautilus Mainnet chain in the project.

Detailed summary

• Added Nautilus chain definition in src/chains/definitions/nautilus.ts
• Nautilus Mainnet chain with ID 22222, native currency ZBC
• RPC URL: https://api.nautilus.nautchain.xyz
• Block explorer: NautScan at https://nautscan.com

✨ Ask PR-Codex anything about this PR by commenting with /codex {your question}