- iterateJournalEpochRows fetches one completed LIMIT statement per page
instead of a lazily consumed .iterate() cursor, so reduction never runs
inside an open read snapshot and a WAL checkpoint can pass mid-replay.
Regression test: a checkpoint issued from inside the reducer is not busy.
- The retention test now asserts the applyJournalRow spy observed every
row, so the 8 MiB bound cannot pass vacuously if the spy stops
intercepting.
- Reliability gate manifest records the new assertion and the paged
read design.