Add EB-Chain (Chain ID: 8721) Support

Hello MetaMask team,

We would like to request support for EB-Chain in MetaMask.

Network Details:
- Name: EB-Chain
- Chain ID: 8721 (0x2211)
- RPC URL: https://rpc.ebcscan.net
- Block Explorer: https://ebcscan.net
- Currency Symbol: EBC
- Status: Live/Production

EB-Chain is a fully operational EVM-compatible blockchain with:
✅ Unique Chain ID (verified)
✅ HTTPS infrastructure
✅ Active block explorer
✅ Production-ready network

We have already submitted to ethereum-lists/chains for official listing.

Thank you for considering this addition.

Start by inspecting the repository's existing network or chain metadata entry points and compare them with the submitted EB-Chain details. Check the ethereum-lists/chains listing mentioned in the issue and verify the RPC URL, chain ID, explorer, and currency symbol. Done means the repository has the appropriate EB-Chain support and its existing validation checks pass.

Written by the indexing model from the issue text.