Billing metrics

{
  created_at: string, // Timestamp for when the event was created
  tenant_id: string, // Poolside tenant that originated the request
  usage_per_model_type: {
    "<model-type>": { // For example: "chat" or "completion"
      tokens_in: number, // Number of input tokens
      tokens_out: number // Number of output tokens
    }
  },
  identity_count: number, // Number of users who can sign in to Poolside
  prompted_identity_count: number // Number of users who have started at least one conversation in the tenant
}