apexLookupRule mapped every findApex failure to Crit, including transport
and resolver faults like "lookup nemunai.re on 127.0.0.11:53: server
misbehaving" — a flaky recursive resolver, not a broken delegation. That
made the check flap into Crit whenever the resolver hiccuped, the same
class of false negative the chain path already fixed.
Mark apex-lookup failures that stem from a transport/resolver fault
(resolveZoneNSAddrs net errors, recursiveExchange transport errors, and
SERVFAIL/REFUSED seen during the SOA walk) as transient via a typed
error, surface it as ApexLookupTransient, and have apexLookupRule report
Unknown for those. Definitive failures (NXDOMAIN-only walk, no resolvable
NS) still drive Crit.
