curl --request GET \
  --url http://localhost:8080/polls/{poll_id}/stats

{
  "poll_id": 123,
  "poll_title": "<string>",
  "total_responses": 123,
  "completed_responses": 123,
  "reward_sum_kopeks": 123,
  "reward_sum_rubles": 123,
  "questions": [
    {
      "id": 123,
      "text": "<string>",
      "order": 123,
      "options": [
        {
          "id": 123,
          "text": "<string>",
          "count": 123
        }
      ]
    }
  ]
}