The set of revealed event ids lived on TimelineProtectionPresenter, which is
scoped to the room graph. That graph is rebuilt every time the room is opened,
so the set was empty on re-entry and every revealed image was hidden again.
Move it into a session scoped TimelineProtectionStore. The store is in memory
rather than persisted: revealing media is a privacy control and there is no
hide action today, so keeping the reveals for the session leaves restarting the
app as a way to undo one, and the set is dropped on logout.
hayaksi1
6533a10ab9