- Restore the unconditional baseRowId/defaultRowCommitVersion assertions
  in checkActionsWrittenInJson for both V1 and V3. The previous change
  weakened coverage by skipping the V3 assertion, but the E2E tests
  always pass empty values so the assertion should remain.
- Extract commitSingleAction helper to reduce boilerplate and avoid
  scoping issues with scalafmt.
- Simplify regression test assertions (remove redundant message strings).