Today’s chore list. Rolls over to an empty list if local midnight has
passed since it was last entered (a chore post-it is a fresh thing each
morning), persisting the reset so the overlay and the settings editor
always agree on “today”.
Replace today’s chore list with the user’s edited lines. The list is
trimmed, de-blanked, and capped before it is stored, so the overlay only
ever sees clean, bounded text. Returns the stored state so the editor can
re-seed from the canonical (sanitized) list.