The fail-closed crypto loader throws a stack trace on a missing/short
ENCRYPTION_KEY rather than a sentence an operator can act on, and
check-env is a dev/CI tool the image operator never runs. Add a boot-time
readiness summary (instrumentation register) that prints a clear line per
core secret — with the exact openssl fix on a bad one — before anything
throws, plus a one-glance status of the optional channels and the
Secure-cookie transport hint. Never logs secret values; never throws.
