curl --request POST \
  --url https://api.callhq.ai/api/chats \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '{
  "sessionId": "<string>",
  "input": "<string>",
  "assistantOverrides": {
    "variableValues": {}
  }
}'

{
  "message": "<string>",
  "chat": {
    "id": "<string>",
    "externalChatId": "<string>",
    "sessionId": "<string>",
    "input": "<string>",
    "output": [
      {
        "role": "user",
        "content": "<string>"
      }
    ],
    "assistantId": "<string>",
    "status": "<string>",
    "cost": 123,
    "createdAt": "2023-11-07T05:31:56Z",
    "updatedAt": "2023-11-07T05:31:56Z",
    "assistantOverrides": {
      "variableValues": {}
    }
  }
}