Migrate from Dune Sim to GoldRush

// BEFORE -- Sim: X-Sim-Api-Key, numeric chain IDs.
// (api.sim.dune.com stopped serving on 2026-08-01.)
const res = await fetch(
  "https://api.sim.dune.com/v1/evm/balances/" + address + "?chain_ids=1,8453",
  { headers: { "X-Sim-Api-Key": process.env.SIM_API_KEY } }
);
const { balances } = await res.json();

// AFTER -- GoldRush: Bearer auth, named chain slugs.
const res = await fetch(
  "https://api.covalenthq.com/v1/allchains/address/" + address +
    "/balances/?chains=eth-mainnet,base-mainnet",
  { headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY } }
);
const { data, error, error_message } = await res.json();
if (error) throw new Error(error_message);
const balances = data.items;

// BEFORE -- Sim took numeric EVM chain IDs.
const SIM_CHAINS = [1, 8453, 42161, 137];

// AFTER -- GoldRush takes named slugs. Rather than hardcoding a map,
// build it once from the live chain list so it never drifts.
const res = await fetch("https://api.covalenthq.com/v1/chains/", {
  headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY },
});
const { data } = await res.json();
const byChainId = new Map(data.items.map((c) => [Number(c.chain_id), c.name]));

const SIM_CHAINS = [1, 8453, 42161, 137];
const chains = SIM_CHAINS.map((id) => byChainId.get(id)).filter(Boolean);
// -> ["eth-mainnet", "base-mainnet", "arbitrum-mainnet", "matic-mainnet"]

// BEFORE -- Sim used limit/offset.
let offset = 0;
const all = [];
for (;;) {
  const res = await fetch(
    "https://api.sim.dune.com/v1/evm/transactions/" + address +
      "?limit=100&offset=" + offset,
    { headers: { "X-Sim-Api-Key": process.env.SIM_API_KEY } }
  );
  const body = await res.json();
  all.push(...body.transactions);
  if (body.transactions.length < 100) break;
  offset += 100;
}

// AFTER -- GoldRush pages by number in the path.
// Page 0 is the OLDEST page, so this walks forward in time.
let page = 0;
const all = [];
for (;;) {
  const res = await fetch(
    "https://api.covalenthq.com/v1/eth-mainnet/address/" + address +
      "/transactions_v3/page/" + page + "/",
    { headers: { Authorization: "Bearer " + process.env.GOLDRUSH_API_KEY } }
  );
  const { data, error, error_message } = await res.json();
  if (error) throw new Error(error_message);
  all.push(...data.items);
  if (!data.links?.next) break;
  page += 1;
}