feat(#2392): group boot sweep + reconciles under one boot dag

hive-sh4re/src/jobs.rs

@@ -40,6 +40,10 @@ pub enum Template {
     /// Bare converge of observed power state to the persisted intent
     /// (boot reconcile).
     Reconcile,
+    /// Boot-time root anchor: a single no-op node that groups this boot's
+    /// `StartupSweep` + per-agent `Reconcile` child DAGs under one tree, so the
+    /// dashboard renders the whole boot as one entry instead of N+1 rows.
+    Boot,
 }
 
 impl Template {
@@ -57,6 +61,7 @@ impl Template {
             Template::Start => "start",
             Template::Stop => "stop",
             Template::Reconcile => "reconcile",
+            Template::Boot => "boot",
         }
     }
 }