rebuild_queue: wire worker into coordinator + dashboard event

hive-c0re/src/main.rs

@@ -233,6 +233,18 @@ async fn cmd_serve(
     // Reminder scheduler: drains due reminders + handles
     // file_path payload persistence. See reminder_scheduler.rs.
     reminder_scheduler::spawn(coord.clone());
+    // Rebuild-queue worker: drains the global rebuild/meta-update/
+    // spawn queue FIFO so hive-c0re never runs two heavyweight
+    // container ops concurrently. Existing rebuild call sites
+    // (auto_update, dashboard, manager, approval handler) enqueue
+    // here instead of awaiting `rebuild_agent` inline. See
+    // `rebuild_queue.rs`.
+    {
+        let q_coord = coord.clone();
+        tokio::spawn(async move {
+            rebuild_queue::run_worker(q_coord).await;
+        });
+    }
     // Forward every broker event onto the unified dashboard
     // channel with a freshly-stamped seq, so the dashboard SSE
     // sees broker messages + future mutation events on one