* feat(subscriber): award mystery items at cron
* fix(mystery): backfill skipped months
* fix(mystery): adjust subscriber text
* fix(mystery): correct moment logic
and remove irrelevant tests
* fix(mystery): build set one month in advance
* fix(mystery): don't add empty set to Time Travelers
* refactor(mystery): readability
* feat(subscription): promo banner in modal
* feat(subscription): promo banner on main page
* fix(banners): remove extraneous margin adjustment
* fix(banners): various
* feat(promotion): gift 1, get 1
* fix(promo): various
* chore(promo): add Bailey
* fix(promo): use different email template for promo beneficiary
* fix(promo): turns out Winter is meaningful
* fix
Newly subscribed accounts receive erroneous notification that they have Mystery Items
* Added unit test for #10496
* Restored a previous unit test