Add Robinhood Chain (chain 4663)

[ScreamingHawk]

Summary

Adds Robinhood Chain (chain 4663) to @0xsequence/network. The chain has no entry, so networks[4663] is undefined — consumers get no chain title, logo or block explorer URL for Robinhood.

• ChainId.ROBINHOOD = 4663
• networks[ChainId.ROBINHOOD] — title "Robinhood Chain", explorer https://robin.etherscan.io/, native token ETH (18 decimals)
• createNetworkConfig(ChainId.ROBINHOOD) in allNetworks

Robinhood Chain is an Arbitrum-stack L2 with ETH gas, so the native token is ETH rather than a stablecoin. The explorer URL matches the one the relay chain list already uses for this chain.

Draft

Left as a draft pending Robinhood support elsewhere in the stack — the network entry is ready to land once that is in place.

Verification

• tsc --noEmit clean at the repo root.
• networks[4663] resolves, allNetworks includes it, and getChainIdFromNetwork('robinhood') returns 4663, confirmed by importing the source.
• Chain ID confirmed against the live RPC (eth_chainId returns 0x1237 = 4663).
• The logo asset https://assets.sequence.info/images/networks/medium/4663.webp returns 200.
• eslint and prettier clean on the touched files.