Add Robinscan explorer for Robinhood Chain (eip155-4663)

[robinscan]

Adds Robinscan as a block explorer for Robinhood Chain (chain ID 4663), alongside the existing Blockscout explorer.

[github-actions]

You successfully submitted a PR! Due to the amount of PRs coming in: we will only look at PRs that the CI is happy with. We can also not hold your hand getting the CI green - just look how others that where merged did it and RTFM. So as long as there is any CI check that reports an error - no human will look at this. You might be able to ask for some support after supporting the project - e.g. by sending funds to lists.eth. When you fixed things after a requested change - then you also need to (re-)request a review.

[robinscan]

@ligi thanks for updating the branch — quick heads-up: the build failure that came with it is unrelated to this PR's changes.

_data/chains/eip155-4663.json also lists https://hoodscan.ai (added in #8512), which has been returning 402 with x-vercel-error: DEPLOYMENT_DISABLED for more than a week. That's not a transient error — the deployment was switched off, so the explorer check will keep failing for any PR touching this chain file, not only this one.

Since we're adding an explorer for the same chain, we'd rather not remove another project's entry unprompted — so we've opened #8601 with the removal, for you to merge or close as you prefer. It can always be re-added if the site comes back.