status: one machine that cannot be worked out no longer takes the answer from the rest

`status --json` emitted no JSON at all when a single node was unresolvable. A blocked
node is not on the private network, and a mesh whose hub is that node has no hub — which
came back through the reading as a refusal, so `status` printed nothing and `status
--json` put multi-line prose on stderr and not one byte on stdout. A machine-readable
interface that stops being machine-readable exactly when something is wrong is one nobody
can build an alarm on.

Why a machine cannot be worked out is read as data now, per machine, through the same
whoResolves the private network is built from — so this and the network agree about who
could not be resolved rather than deciding it twice. The private network failing to
compute is kept as a note beside it instead of ending the read: it is almost always a
consequence of those same refusals, and every question that does not depend on it is
still answered.

It reaches all three ways of saying it, from the one reading: the text form leads with it
because a machine here is in none of the answers below, the JSON carries `unresolved`
(always a list, never null) and `network`, and the page has a section of its own.

That also closes a silent success. A machine that resolves to nothing has nothing
computed for it, so there is nothing to compare it against and nothing it can be behind —
it appeared in no answer at all, and `status` reported a mesh where nothing could be sent
anywhere as "all doing what they were told".

statusAsJSON takes the whole reading now rather than a growing argument list, which is
what let an answer be added to the text form and forgotten here. The two are one
function's output in two shapes and must not be able to differ about what was asked.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

cmd/mesh-control/build.go

@@ -442,4 +442,13 @@ type answers struct {
 	// pair that answers "has it caught up", which waiting alone cannot (the sent digest is
 	// recorded at send, not at apply).
 	reported []inventory.Reported
+	// refused is why a machine cannot be worked out at all, by name. A different thing from every
+	// other answer here: those are about a machine that was told something, and this is about one
+	// that cannot be told anything — it never reaches waiting, because nothing was computed for it
+	// to compare against, so without this a wholly blocked mesh reads as a well one.
+	refused map[string]string
+	// network is why the private network could not be computed, when it could not. Almost always
+	// a consequence of the refusals above: a node that does not resolve is not on the network, and
+	// a mesh whose hub is that node has no hub.
+	network string
 }