Status notes (the per-metric text a model writes) move out of audit_logs
into InsightStatusCache: one row per user, metric and locale, the note
encrypted at rest, upserted in place, with the input and snapshot
fingerprints and a separate negative-cache window.
Migration 0344 creates the table and deletes every audit_logs row whose
action matches insights.%-status.%. The notes are a regenerable cache and
the old rows are plaintext, so nothing is copied; the first nightly run
after the upgrade writes them again. Take a backup before applying.
The table is registered for key rotation, excluded from backups as a
regenerable cache, and deleted by Delete All Data.
Refs #975
