186b7d5ea5
The last pages of a deep reverse page-through on a forward-only backend each walked down to 1970 one x4 growth step at a time (~14-16 reads, ~2.5 s live). After two empty segments the walk now asks once per page for the whole remainder at the page budget (a truncated answer is discarded and the walk carries on), and the stretch the page's last complete read proved empty rides the continuation point (HistoryContinuationState.EmptyFromTicks/EmptyToTicks, session-held, so no versioning) so the next page steps over it. Fuzz now pages with the walk's own hints and with true random empty stretches.