The core-package e2e tests cover each generator in isolation. None
exercised generators running in sequence — so the feature template
shipping without an integrations/cms/index.ts barrel went unnoticed
until `gen job` failed against a scaffolded feature.
This test scaffolds a feature, then runs `gen job` against it. `gen job`
throws at its `<gen:job-tasks>` anchor assertion if the barrel is
missing, so the composition gap now fails loudly.