Install tini in the container image and route ENTRYPOINT through
`/usr/bin/tini -g -- /opt/hermes/docker/entrypoint.sh`.
Without a PID-1 init, orphans reparented to hermes (MCP stdio servers,
git, bun, browser daemons) never get waited() on and accumulate as
zombies. Long-running gateway containers eventually exhaust the PID
table and hit "fork: cannot allocate memory".
tini is the standard container init (same pattern Docker's --init flag
and Kubernetes pause container use). It handles SIGCHLD, reaps orphans,
and forwards SIGTERM/SIGINT to the entrypoint so hermes's existing
graceful-shutdown handlers still run. The -g flag sends signals to the
whole process group so `docker stop` cleanly terminates hermes and its
descendants, not just direct children.
Closes#15012.
E2E-verified with a minimal reproducer image: spawning 5 orphans that
reparent to PID 1 leaves 5 zombies without tini and 0 with tini.
