docker compose exec db pg_dump -U listmonk -Fc listmonk > listmonk-backup.dump

Runs pg_dump inside the db service and writes a compressed custom-format dump to the host shell, keeping the backup off the container filesystem. The -Fc custom format compresses well and restores with pg_restore. Replay it with `docker compose exec db pg_restore -U listmonk -d listmonk < listmonk-backup.dump`.