List agent executions

curl --request GET \
  --url https://api.zavu.dev/v1/senders/{senderId}/agent/executions \
  --header 'Authorization: Bearer <token>'

{
  "items": [
    {
      "id": "<string>",
      "agentId": "<string>",
      "status": "success",
      "inputTokens": 123,
      "outputTokens": 123,
      "latencyMs": 123,
      "cost": 123,
      "createdAt": "2023-11-07T05:31:56Z",
      "inboundMessageId": "<string>",
      "responseMessageId": "<string>",
      "responseText": "<string>",
      "errorMessage": "<string>"
    }
  ],
  "nextCursor": "<string>"
}