curl -X POST https://api.relayer.fi/v1/action/builders/swap \
  -H "Authorization: ApiKey $RELAYER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "tokenIn":  "0xA0b86a33...",
    "tokenOut": "0xC02aaA39...",
    "chain":    "base",
    "title":    "Swap USDC → WETH"
  }'

{
  "success": true,
  "metadata": {}
}