Stop persisting checkpointDiffLoaded in turn diff summaries

- Remove `checkpointDiffLoaded` from hydration and persistence paths
- Update persistence schema tests to assert loaded flags are cleared
ba1a2dbcf7Julius Marminge committed on 2/19/2026, 5:59:17 AM· committed by Julius Marmingeparentb441875
2 files changedLine totals unavailable