fix(backends,conversations,telegram,ui): a background subagent reports back as its own turn

ui/src/lib/panel/activity-feed.svelte

@@ -23,7 +23,7 @@
 
   onMount(() => {
     const timer = setInterval(() => {
-      if (model.running) {
+      if (model.live.length > 0) {
         now = Date.now();
       }
     }, TICK_MS);