jobq: delete DagView/NodeView, the second projection of one graph

Two views of the same graph existed: the typed `DagView`/`NodeView`
(`/api/state.rebuild_queue`, the `QueueDag` socket request, and the
`RebuildQueueChanged` payload) and `hive-jobq-wire`'s generic
`GraphNode` (`/api/jobq/graph`, `QueueNodes`). Every consumer has moved
to the generic one, so the typed pair is deleted rather than kept in
agreement with it.

What that removes, beyond the types: the `QueueDag` request and
`HostResponse::dags`; `Queue::snapshot`; `dag_view`, `visible_dags`,
`shown_on_wire`, `dag_finished_at` and `containers`; and the
`rebuild_queue` field on `/api/state`. `RebuildQueueChanged` keeps its
seq and loses its payload — nothing read it, and shipping the graph
both on an event and on an endpoint is the duplication this issue is
about. It stays an event rather than becoming a poll because
push-on-change is what every other live surface here does.

Two behaviours came out simpler for a structural reason. `await_dags`
needed two rules — settled means "gone from the snapshot" *or* "present
with every node terminal" — because the typed view evicted finished
groups; the generic view doesn't, so pending is just "some node isn't
terminal". And `state_of` in the tests no longer derives a roll-up at
all: a group root's own state is the scheduler's answer.

That second one found a bug. `cancelled_dag_still_runs_its_approval
tail` asserted the group reads `Cancelled` while the tail it exists to
protect was still pending — `rollup_state` flattened the surviving
child away and called the group settled. The root reads `Finishing`,
which is what the scheduler documents: own logic done, children still
running. The test now asserts that, with the reasoning inline so it
doesn't get "fixed" back.

Kept: `Source`, `State`, `PermPayload` and the `NodeId` alias in
`hive-host-sock::jobs` — shared vocabulary, still used by hivectl.

hive-c0re/src/dashboard/state_snapshot.rs

@@ -78,13 +78,6 @@ pub(super) struct StateSnapshot {
     /// disabled "updating…" state; live transitions arrive via the
     /// `MetaUpdateRunning` event.
     meta_update_running: bool,
-    /// Current state of the global job queue — pending + running DAGs
-    /// (rebuild / meta-update / spawn / power ops) with their per-node
-    /// breakdowns, plus the most recent few terminal DAGs the queue
-    /// retains for history. Live transitions arrive via the
-    /// `RebuildQueueChanged` event. See `job_queue/`. Field name kept
-    /// from the old flat queue for wire compatibility.
-    rebuild_queue: Vec<crate::job_queue::DagView>,
     /// Whether the hive-forge container is up. When true the dashboard
     /// links each container's config + each approval's commit into the
     /// forge's `agent-configs` repos.
@@ -424,7 +417,6 @@ pub(super) async fn api_state(
         question_history,
         tombstones,
         port_conflicts,
-        rebuild_queue: state.coord.job_queue.snapshot(),
         forge_present: crate::forge::is_present().await,
         matrix_gui_enabled: std::env::var_os("HIVE_MATRIX_GUI_ENABLED").is_some_and(|v| {
             // Accept any truthy string ("1", "true", "yes") since the