Two defects found live in the v3.8.45 Phase 5 run (2026-07-06):
- execFileSync default 1 MiB maxBuffer crashed on git show origin/main:CHANGELOG.md
- the i18n resync only synced the [NEXT] (TBD) section, leaving the just-shipped
finalized section as '— TBD' in all 42 mirrors; now also syncs [prevVersion]
bounded by the heading below it (new pure helper versionAfter, unit-tested)