A grant is an order without money, not a second code path: GrantSubscription
and GrantAddon create the same Order/Subscription/SubscriptionAddon rows a
paid purchase does, with stripe_subscription_id left null and price_cents set
to whatever the customer actually pays. OpenSubscription and BookAddon gained
an optional overrides parameter so the price and provenance (who granted it,
when, a note, an optional end date, and the catalogue price for legibility)
land on the same snapshot every real purchase goes through, not a duplicate.
New customers.grant_plan capability, Owner-only like secrets.manage — giving
away service is exactly the kind of blast radius that precedent reserves for
the Owner.
nexxo