- verify_submit now applies the subscribe checkbox only at first sign-up.
Returning users keep whatever they set via Settings or the one-click
unsubscribe link — previously, every login silently re-enrolled them.
- JOB_NAMES gains email_digest_job so the ops footer reflects its health.
Adds tests/test_verify_subscribe.py::test_returning_user_login_preserves_unsubscribe.