Redis without a password was the root cause of the security incident
(cron miner via unauthenticated replication RCE, see
.forcc/deploy/SESSION2-FINDINGS.md). Loopback binding alone doesn't
protect against a compromised container inside the same compose
network, so wire REDIS_PASSWORD as a required secret everywhere redis
is used: backend/worker/worker-transcriber(-gpu), redis-exporter,
livekit and egress (via rendered templates). docker compose now
refuses to start without it instead of silently running unauthenticated.
