curl --request POST \
  --url https://app.vaultgraph.com/api/signing-keys \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "public_key": "<string>"
}
'

{
  "created": false,
  "data": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "key_fingerprint": "<string>",
    "status": "active",
    "public_key": "<string>"
  }
}