Address review findings on the title-clamp: TITLE_MAX_LEN now reads the length straight
from Notification.title so the clamp can't drift from the column a migration would change
(single source of truth). Add a db-lane test that actually commits a >255-char title into
Postgres (end-to-end proof the truncation is gone, not just the clamp logic) and one that
asserts the constant tracks the column width.