curl --request GET \
  --url http://localhost:3000/flags/{flagId}/metrics \
  --header 'Authorization: Bearer <token>'

{
  "statusCode": 123,
  "message": "OK",
  "data": {
    "totalEvaluations": {
      "value": 123,
      "change": 123
    },
    "uniqueUsers": {
      "value": 123,
      "change": 123
    },
    "successRate": {
      "value": "<string>",
      "change": 123
    },
    "errorRate": {
      "value": "<string>",
      "change": 123
    },
    "avgResponseTime": {
      "value": "<string>",
      "change": 123
    },
    "variationPerformance": [
      {
        "key": "<string>",
        "name": "<string>",
        "evaluations": 123,
        "percentage": 123
      }
    ]
  }
}