Enable or disable usage-based billing for the tenant (PRODUCT-3245). When disabled, the UI hides every billing surface for the tenant — invoices, payment methods, plan and subscription screens. Defaults to enabled.

The flag is a presentation opt-in: nothing in ingestion, rating or invoicing is gated on it. The same value is exposed on the tenant stub returned by GET /v2/api/users/me, which is where the front end reads it before first paint.