Replace the entity slugs on organizations, workspaces, resource pools,
and
plan ladders with nullable `key` columns and add keys to products,
prices,
and entitlement sets. Rename `providers.slug` to `provider` and add
partial
unique indexes for system and org role names.
Assign invoice numbers per billing account from a gapless transactional
counter; Stripe's number moves to the invoice mapping as an external
reference.
Seeds, fixtures, and the operator lookup address rows by key, and the
returning-login resync no longer blanks a display name when the IdP
sends
no `name` claim.