curl --request GET \
  --url https://api.specular.dev/projects/{id}/ai-gateway/usage \
  --header 'Authorization: Bearer <token>'

{
  "usage": [
    {
      "id": "<string>",
      "projectId": "<string>",
      "branchId": "<string>",
      "model": "<string>",
      "requestPath": "<string>",
      "inputTokens": 123,
      "outputTokens": 123,
      "costUsd": 123,
      "requestedAt": "2023-11-07T05:31:56Z"
    }
  ],
  "total": 123,
  "limit": 123,
  "offset": 123
}