Add blocklist entry

curl --request POST \
  --url https://sandbox.clausum.ai/api/v1/blocklists \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "list_type": "email",
  "value": "fraudster@example.com",
  "severity": "block",
  "reason": "Confirmed chargeback fraud"
}
'

{
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "organization_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "value": "<string>",
  "reason": "<string>",
  "is_active": true,
  "expires_at": "2023-11-07T05:31:56Z",
  "created_at": "2023-11-07T05:31:56Z"
}