The taxpayer's zone decides which tax month an income is filed under, and the
config refuses to boot on a zone it cannot resolve rather than misfiling into
UTC. That correctness was resting on the base image happening to ship
/usr/share/zoneinfo — true of distroless/static-debian12 today, but not a thing
to leave implicit on a path where being wrong means a wrong tax return.
Costs about 450 KB of binary. Adds a config test pinning the default zone and
the hard failure on an unknown one.
Ilia Denisov