Persists this run's entire stdout/stderr transcript to BACKUP_DIR (/volume1/SMB-docker/backup) — the same directory the pg_dumpall backup lands in. Appends to an already-open CUTOVER_SESSION_LOG if invoked as a child of cutover.sh (merging into that session's single transcript); opens its own rollback-standalone-<TS>.log if run standalone (including a manual run long after the fact, per this script's own asymmetry warning). This is the single highest-value place for a durable transcript in the whole suite, since rollback.sh failing partway is the one scenario RUNBOOK.md flags as requiring manual intervention. Also logs the transcript path in the grace-window refusal message so it's not lost even in that failure mode. Console/SSH output unchanged (tee mirrors to both). See ADR-0001 note, Session Update 9.