curl --request POST \
  --url https://api.neynar.com/v2/farcaster/signer/signed_key/ \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '{
  "signer_uuid": "19d0c5fd-9b33-4a48-a0e2-bc7b0555baec",
  "signature": "<string>",
  "app_fid": 3,
  "deadline": 123,
  "redirect_url": "<string>",
  "sponsor": {
    "fid": 3,
    "signature": "<string>",
    "sponsored_by_neynar": true
  }
}'

{
  "object": "signer",
  "signer_uuid": "19d0c5fd-9b33-4a48-a0e2-bc7b0555baec",
  "public_key": "0x3daa8f99c5f760688a3c9f95716ed93dee5ed5d7722d776b7c4deac957755f22",
  "status": "generated",
  "signer_approval_url": "<string>",
  "fid": 3,
  "permissions": [
    "WRITE_ALL"
  ]
}