hive-host-sock: a jobq graph wire type that doesn't know what a node is

`jobs::NodeView` can only ever display hive-c0re's queue. Five of its
fields are domain knowledge: `approval_id` is only ever on a
`DeployWindow`, `inputs` only on a `MetaLock`, `build_log_id` only on the
nix-heavy kinds, `agent` is derived from the payload, and `kind` is a
payload tag consumers branch on. A component built against that shape
cannot render a second jobq.

`graph::GraphNode` is `hive_jobq::Node` with both generics erased: the
crate's own field set, with everything domain-specific in one opaque
`payload.data` slot the consumer renders without branching on. That is
the crate boundary made visible — hive-jobq owns structure, its host owns
meaning — and it is the same split #2957 drew inside the code.

Two details that are easy to get wrong and are pinned by tests:

`GraphDep::Node` carries `accepts` as the **set** of terminal outcomes,
not a strong/weak flag. A template emits its tails as a pair edged on the
same upstream node, and the only thing telling them apart is which
outcomes each accepts; collapsing that renders two structurally different
nodes identically.

There is **no roll-up field**. A group root ships as an ordinary node
with `parent: None`, and its own `state` is its subtree's answer —
`Finishing` means "own logic done, children still running", the terminal
states are the rolled-up outcome. A separate field would be a lossier
copy: `DagView::rollup_state` flattens `Running` and `Finishing` into
one, which is exactly the distinction a viewer wants.

`State` and `TerminalState` are re-exported from `hive-jobq` rather than
redeclared, so they cannot drift from the scheduler that produces them.

Cargo.lock

@@ -1727,6 +1727,7 @@ dependencies = [
  "hive-sh4re",
  "hive-types",
  "serde",
+ "serde_json",
 ]
 
 [[package]]