Checkout, invoices, and per-workspace Stripe customers
Stripe Checkout for new subscriptions and upgrades, with invoice history on the workspace.
Added
3- BillingStripe Checkout sessions for new subscriptions and for upgrading an existing one.
- BillingEach workspace gets its own Stripe customer, with a duplication check so a retry cannot create a second one.
- BillingInvoice history, exposed through an API and shown on the workspace.