Third boot failure: the exporter exited 100 ms in with 'unknown long
flag --listen-address' (proved against the pinned image, plus --help).
The bind semantics were right; the flag name was invented. --web.listen-address
is repeatable - one per address - so the dual gateway+LAN bind stands.
Proven again pre-deploy with the real argv: the run starts and dies
only on the deliberate /dev/null placeholder config.