- providers/xai-billing.js: fetchXaiUsage, fetchXaiInvoicePreview,
aggregateByKey, renderXaiSection
- analyze.js: --xai flag for standalone view; xAI section appended
to full report when XAI_MANAGEMENT_KEY is set
- Verified against live API: per-key spend by unit type, prepaid
balance, current billing period total
- Usage endpoint: POST /v1/billing/teams/{id}/usage (analyticsRequest)
- Invoice endpoint: GET /v1/billing/teams/{id}/postpaid/invoice/preview
