curl --request POST \
  --url https://api.0xarchive.io/v1/web3/signup \
  --header 'Content-Type: application/json' \
  --data '
{
  "message": "<string>",
  "signature": "0x..."
}
'

{
  "api_key": "0xa_live_abc123...",
  "tier": "free",
  "wallet_address": "<string>"
}