jobq-wire: move the generic graph projection into its own crate

The wire types were in hive-host-sock, which is the host *socket* crate — so
anything living there is core-shaped by construction, and the projection had
quietly grown two core dependencies to match: it selected roots by matching
NodeKind::Dag, and rendered payloads through free functions in hive-c0re that
nothing obliged a second host to write.

hive-jobq is the wrong home too. That crate is the scheduler — logic — and
folding presentation in means every consumer of it carries a JSON vocabulary
it may never serve.

So: a new hive-jobq-wire. A host implements WireNode for its payload N and
WireResource for its resource name R; GraphWire::wire_snapshot is
blanket-implemented for Graph<N, R> when both hold, and for nothing else. A
payload that has never said how it displays has no way onto the wire.

wire_snapshot takes the roots to serve rather than reading Graph::roots
itself. Nothing is ever removed from a Graph, so retention is a policy only
the host can hold; hive-c0re passes visible_roots(), which is the existing
MAX_HISTORY_DAGS bound selected structurally (a root is a node with no
parent) instead of by node kind.

Cargo.lock

@@ -1636,6 +1636,7 @@ dependencies = [
  "hive-core-agent-sock",
  "hive-host-sock",
  "hive-jobq",
+ "hive-jobq-wire",
  "hive-priv-sock",
  "hive-sh4re",
  "hive-sock-client",
@@ -1727,7 +1728,6 @@ dependencies = [
  "hive-sh4re",
  "hive-types",
  "serde",
- "serde_json",
 ]
 
 [[package]]
@@ -1742,6 +1742,16 @@ dependencies = [
  "uuid",
 ]
 
+[[package]]
+name = "hive-jobq-wire"
+version = "0.1.0"
+dependencies = [
+ "chrono",
+ "hive-jobq",
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "hive-matrix-mcp"
 version = "0.1.0"