refactor(#2591): fix wire-shape consumers (server await_dags, tests)

- server::await_dags: a DAG is settled when gone from the snapshot (fully
  Done) or present with all nodes terminal; pending only with a non-terminal
  node (DagView no longer carries a rolled-up state).
- DagView::rollup_state() added to hive-sh4re — the shared node-set roll-up
  derivation every Rust consumer uses.
- JobQueue::build_log_id_of(node_id) — the node_id -> build_logs lookup the
  query endpoint will use; tests assert log-id via it now.
- tests: derive roll-up state; drop the off-wire step/build_log_id wire asserts.

hive-c0re/src/job_queue/mod.rs

@@ -361,7 +361,6 @@ impl JobQueue {
         let mut inner = self.lock();
         let inner = &mut *inner;
         let started = inner.sched.settle();
-        let now = now_unix();
         let mut claims = Vec::with_capacity(started.len());
         for id in started {
             let Some(node) = inner.sched.graph().node(id) else {
@@ -511,6 +510,17 @@ impl JobQueue {
         true
     }
 
+    /// The `build_logs` row id linked to `node_id`, if any — the lookup behind
+    /// the `GET /api/build-log/<node_id>` query endpoint (the client fetches a
+    /// node's captured build output on demand rather than receiving it inline).
+    #[must_use]
+    pub fn build_log_id_of(&self, node_id: NodeId) -> Option<i64> {
+        self.lock()
+            .node_rt
+            .get(&node_id)
+            .and_then(|r| r.build_log_id)
+    }
+
     /// A DAG's terminal roll-up summary, computed on demand from its container.
     /// `None` if the DAG id is unknown. Test-only — production reads the summary
     /// `complete_node` returns when the container rolls up terminal.