curl --request PUT \
  --url https://synthesis.trade/api/v1/project/account/{account_id}/metadata \
  --header 'Content-Type: application/json' \
  --header 'X-PROJECT-API-KEY: <api-key>' \
  --data '{
  "metadata": {}
}'

{
  "success": true,
  "response": {
    "account_id": "01234567-89ab-cdef-0123-456789abcdef",
    "metadata": {},
    "created_at": "2026-01-01T00:00:00"
  }
}