b9d5f54 (stealth TURN discovery) emits a top-level `sni_router:` block
into node.yaml unconditionally, but only added a lenient ad-hoc parse
in the carry-forward logic — not the field on config.Config that
orama-node strict-decodes (KnownFields(true)) at boot. Identical
failure mode to the v0.122.42 secrets_encryption_key incident: the
unknown key fails the whole node.yaml parse and orama-node crash-loops.
Caught pre-deploy this time by the strict-decode gate check; devnet
never saw it. Regression test added alongside the v0.122.42 one in
decode_test.go.
