Finish adding a passkey

{
  "passkey": {
    "id": "01M5Y1G7AF0N78A9EP71BV68MT",
    "name": "MacBook",
    "device_type": "multiDevice",
    "backed_up": true,
    "transports": [
      "internal"
    ],
    "created_at": "2026-10-27T09:30:00+00:00",
    "last_used_at": null
  }
}