jobq: key transient tombstones per pill, not per agent

Deletes `TransientState`, adds `transient_kind` to `TransientCleared`, and
fixes a crash misreport — three changes over the same functions.

`TransientState` was `RunningTransient` with `agent` dropped and
`takes_container_down` renamed; that rename was the only thing it did, and
its three consumers each read a disjoint subset. `transient_snapshot` now
returns `RunningTransient` directly.

`recent_transient` was keyed by agent alone and overwritten on each clear.
An agent can clear several pills in one grace window, so a `Prebuild`
(`takes_container_down = false`) landing after a `StopForUpdate` (`true`)
left the tombstone reading `false` and the crash watcher reported a
deliberate stop as a container crash. Keyed by `(agent, label)` now, with
`recent_transient_within` folding back per agent by OR — the same question
`crash_watch` asks of the active set.

`TransientCleared` gains the label for the same reason: a client holding
two open pills for one agent could not tell which one a clear referred to.

The out-of-band suppression guard has no node and so no label; it uses
`NO_NODE_LABEL`, angle-bracketed to stay out of the `NodeKind::as_str`
namespace.

hive-c0re/src/job_queue/model.rs

@@ -389,7 +389,7 @@ impl NodeKind {
     }
 
     /// Whether running this node is *expected* to take the agent's container
-    /// down. Feeds `TransientState::deliberate_stop`, which the crash watcher
+    /// down. Feeds `RunningTransient::takes_container_down`, which the crash watcher
     /// reads to tell an intentional stop from a crash.
     ///
     /// This is a **safety** question, not a display one — it decides whether a

hive-c0re/src/job_queue/scheduler.rs

@@ -190,7 +190,7 @@ fn reconcile_transients(coord: &Arc<Coordinator>, prev: &mut TransientSeen) {
             .iter()
             .any(|t| &t.agent == agent && &t.label == label);
         if !still {
-            coord.emit_transient_cleared(agent, *deliberate);
+            coord.emit_transient_cleared(agent, label, *deliberate);
         }
         still
     });