collectIPs only reads HostnameState, but checkDomain only stored
DomainState (nameservers). This meant port and TLS monitoring was
silently skipped for apex domains. Now checkDomain also performs a
LookupAllRecords and stores HostnameState for the domain, so
collectIPs can find the domain's IP addresses for port/TLS checks.
Added TestDomainPortAndTLSChecks to verify the fix.