feat(monitors): a DNS monitor can name a resolver; the host page puts Ansible above Docker (#5214)

DNS monitors take an optional Resolver, a server's IP. Set, the check asks
that server directly for A and AAAA over UDP and records how long it took
to answer; empty keeps today's lookup through the container's resolver.
"Does my local DNS still answer for public names" and "does 1.1.1.1" are
now separate monitors. No new dependency.

On a host's page the Ansible card moves above the Docker list, which can
run to dozens of containers and hid it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/monitors/routes.py

@@ -28,7 +28,7 @@ def _form_opts(form, mtype: str) -> dict:
     if mtype == MonitorType.tcp.value:
         return {"port": form.get("port")}
     if mtype == MonitorType.dns.value:
-        return {"expected_ip": form.get("expected_ip")}
+        return {"expected_ip": form.get("expected_ip"), "resolver": form.get("resolver")}
     if mtype == MonitorType.http.value:
         return {
             "method": form.get("method"),