One invoice, one card, per docs/03-billing-checkout.md — not built yet. Checkout initiation doesn't exist in Paradox Billing yet, so there's nothing real to show here. See services/billing's README.

Install artifacts per owned product, per docs/02-entitlements.md's setup-artifact contract — Billing doesn't implement POST /paradox/provision or GET /v1/orgs/:org/setup yet, so this section has nothing to render.