List API keys

{
  "api_keys": [
    {
      "id": 1,
      "name": "Production API Key",
      "last_used_at": "2025-01-08T15:30:00.000000Z",
      "created_at": "2025-01-01T10:00:00.000000Z"
    },
    {
      "id": 2,
      "name": "Development API Key",
      "last_used_at": null,
      "created_at": "2025-01-05T14:20:00.000000Z"
    }
  ]
}

{
  "api_keys": []
}