jobq: the core alias is a JobBuilder, not a Job

A JobBuilder holds pending nodes that are not in the graph yet — it is
the thing you declare into. Naming the alias Job claimed it was the work
itself, and the name propagated into every parameter derived from it
(job: super::Job in run_node read as if it carried the DAG).

Prose uses meaning the job *queue* are left alone: main.rs's "Job-queue
scheduler" comment and the docs/coordinator.md reference.

315 tests pass unchanged.

hive-c0re/src/workers/auto_update.rs

@@ -327,7 +327,7 @@ pub async fn run(coord: Arc<Coordinator>) -> Result<()> {
 /// kind-derived resources were removed, which drops the agent lease a boot
 /// reconcile needs to not race another DAG's container ops.
 pub(crate) fn boot_nodes(
-    b: &crate::job_queue::Job,
+    b: &crate::job_queue::JobBuilder,
     any_stale: bool,
     fanout: Vec<String>,
     drifted: Vec<String>,