List featured vaults

Returns the admin-curated featured shortlist, one card per logical vault in curated order: display name, marketing description, deployed chains (highest-TVL first), supply token, aggregate TVL, and the highest 7/30/90-day APY across deployments. vault_ids carries per-deployment {chainId}:{address} ids for /v1/vaults/{vault_id} links, in the same order as chains.