usage_events was absent from Database.pruneOperationalLogs, so the
per-tool telemetry log grew unbounded (~187k rows / ~28MB observed) and
became a dominant driver of .fusion DB bloat once runAuditEvents was
already 30-day capped. Prune it on the same operationalLogRetentionDays
cadence, keyed off its `ts` column (not `timestamp`), alongside the other
column-name exceptions. Adds a regression test and changeset.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>