Build login-session into both images as the swapped root shell, add a
quarantine bind mount for telnet (symmetric to SSH), seed transcripts/
dir and service discriminant at entrypoint. Deployer syncs sessrec.c +
Makefile into each build context alongside the existing syslog_bridge
helper. sessrec falls back to /etc/sessrec.service when env is stripped
(busybox /bin/login).