A preferences response cached by a build before eventDefaults existed
drew every default-on event as off in the matrix until the next refetch.
The no-row rule moves to a client-safe module the server read still
wraps, and the matrix applies it when the map is absent.
The /notifications matrix read the constant default table, where the
mood reminder is off, while delivery derives it from the reminder card.
An account receiving the reminder saw every one of its channel switches
off.
The no-row default now lives in one resolver that delivery and the
preferences read both use. GET /api/notifications/preferences publishes
it as `eventDefaults`, the matrix renders a switch without a stored row
from that map, and the reminder card refreshes the matrix when it flips.
Marc-André Bombeck