defer start-after-rebuild to the fast lane so the build lane frees up (closes #2094)

hive-c0re/src/server.rs

@@ -458,14 +458,14 @@ async fn handle_rebuild(coord: &Arc<Coordinator>, name: &str) -> Result<HostResp
     let agent_dir = coord.ensure_runtime(name)?;
     let hive = coord.hive_env();
     let paths = Coordinator::agent_paths(name, agent_dir);
-    let result = lifecycle::rebuild(name, &hive, &paths, true, &|_| (), &|_| ()).await;
+    let result = lifecycle::rebuild(name, &hive, &paths, true, false, &|_| (), &|_| ()).await;
     // Mirror auto_update::rebuild_agent — the manager wants to know
     // about every rebuild attempt regardless of which surface triggered
     // it, especially failures (build error → manager can adjust the
     // agent's agent.nix). Without this the admin-socket CLI was a
     // notify-gap.
     match &result {
-        Ok(()) => {
+        Ok(_) => {
             coord.notify_manager(&hive_sh4re::HelperEvent::Rebuilt {
                 agent: name.to_owned(),
                 ok: true,