Fix Gate and Wild DNS.

Fix Gate and Wild DNS.

Gate could not resolve private domain names.  The ISP link's DNS
servers were listed first in /etc/resolv.conf.  Punted link-local name
resolution and made Gate's legacy resolvers query Core first by making
it the system/default DNS.  Adjusted Core's =10-lan.network= to match.

The DHCP server on the wild Ethernet still had Core as the subnet DNS,
though the stud listener on Gate was recently configured to listen to
The Wild.  Set the DHCP server's DNS option to Gate.  And punted the
~EmitNTP~ and ~EmitSMTP~ settings (which were also unreachable).