Bucket notifications into day groups for a grouped list.
Pure over now, so the boundaries are testable. Input order is preserved
inside every group (the store hands the list back newest-first), and groups
come out in a fixed order with the empty ones dropped. A notification whose
created can't be parsed lands in earlier rather than being dropped —
a broken timestamp must not hide a notification.
Bucket notifications into day groups for a grouped list.
Pure over
now, so the boundaries are testable. Input order is preserved inside every group (the store hands the list back newest-first), and groups come out in a fixed order with the empty ones dropped. A notification whosecreatedcan't be parsed lands inearlierrather than being dropped — a broken timestamp must not hide a notification.