PG008: Use an init process (tini) for proper signal handling and zombie reaping

When your application runs as PID 1 inside a container, the kernel treats it differently: SIGTERM has no default handler and is silently ignored. This means `docker stop` and Kubernetes graceful shutdown signals do nothing. The container just hangs for the full terminationGracePeriodSeconds (default 30s) until it is forcefully killed with SIGKILL. On top of that, PID 1 is responsible for reaping zombie child processes by calling wait(). Most applications never do this, so orphaned children accumulate as zombies until the PID table is exhausted (~32,768 entries), at which point fork() fails and the container becomes unresponsive. A lightweight init process like tini (~25 KB) or dumb-init sits as PID 1, forwards signals to your application, and reaps zombies automatically. Docker provides a --init flag for local development, but Kubernetes has no equivalent runtime flag, so the init binary must be installed in the image.