curl --request POST \
  --url https://api.sumvin.com/v0/agent/token/user \
  --header 'Content-Type: application/json' \
  --header 'x-sumvin-agent-key: <x-sumvin-agent-key>' \
  --data '
{
  "user_id": "<string>"
}
'

{
  "_links": {},
  "token": "<string>",
  "expires_at": 123
}