8809564aad
Reshaped onto main after #1039 landed the coercion engine (typedColumnsFor / epochToIso / coerceForTargetEngine) — this PR is now only the policy delta on top of it: - validateManifest: replace the CLI-only allowEngineSwitch opt-in with a direction rule — sqlite → pg allowed (upload UI and CLI alike), pg → sqlite refused with a message naming the supported direction - importFromPicpeak: derive crossEngine from the manifest's engine (absent field = target engine, the exact pre-change behavior), log it, return it; route passes it through - scripts/migrate-sqlite-to-postgres.js: rely on the shared gate, drop the flag - restore card: direction stated in the intro, cross-engine notice after a converting restore; both strings in en.json + de.json; removed the orphaned settings.backup.picpeak locale node (unreferenced, stale copy) - picpeakCrossEngine.test.js: direction policy, epochToIso (ms, seconds, numeric strings), coerceForTargetEngine units, plus PICPEAK_PG_TEST_URL-gated real-Postgres stored-value assertions Co-authored-by: Paul Nothaft <53005142+the-luap@users.noreply.github.com>