POST /v3/instruments — stock-instrument

Create a stock / equity instrument.

Request:
{
  "data": {
    "type": "stock-instrument",
    "attributes": {
      "ccyCode":            "string (required) — ISO 4217 (e.g. USD, EUR, DKK)",
      "countryCode":        "string (required) — ISO 3166-1 alpha-2 issuer domicile",
      "name":               "string (required) — display name",
      "securityIdentifier": "string (required) — external security identifier (e.g. ISIN)"
    }
  }
}

Response (201 Created):
{
  "data": {
    "id": "string",
    "type": "stock-instrument",
    "attributes": { /* same as request */ }
  }
}