feat(dashboard): 60s base refresh with event-driven immediate updates

Raise the status dashboard base refresh from 10s to 60s, and refresh
immediately (debounced 1.5s) on events between ticks:
- a real chat message arrives in a registered room (index.ts onMessage)
- an agent starts/finishes a run, i.e. activity moves between rooms
  (GroupQueue.setOnActivityChange fired on activeCount changes)

requestImmediateStatusUpdate() drives updateStatus out-of-band via a coalescing
trigger. The existing re-entrancy guard means the base periodic refresh does not
run while an edit-retry is in flight; a refresh requested during that window is
remembered and runs once afterward. Adds createCoalescingTrigger with tests.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/group-queue.ts

@@ -59,12 +59,28 @@ export class GroupQueue {
     return state;
   }
 
+  private onActivityChange: (() => void) | null = null;
+
   setProcessMessagesFn(
     fn: (groupJid: string, context: GroupRunContext) => Promise<boolean>,
   ): void {
     this.processMessagesFn = fn;
   }
 
+  /** Notified when a group starts or finishes a run (activeCount changes). */
+  setOnActivityChange(fn: () => void): void {
+    this.onActivityChange = fn;
+  }
+
+  private notifyActivityChange(): void {
+    if (!this.onActivityChange) return;
+    try {
+      this.onActivityChange();
+    } catch (err) {
+      logger.debug({ err }, 'onActivityChange callback threw');
+    }
+  }
+
   /** Limit concurrency after restart to avoid API rate-limit storms. */
   enterRecoveryMode(): void {
     this.recoveryMode = true;
@@ -528,6 +544,7 @@ export class GroupQueue {
     transitionRunPhase(state, groupJid, 'running_messages', { runId, reason });
     assertRunPhaseInvariants(state, groupJid);
     this.activeCount++;
+    this.notifyActivityChange();
 
     logger.info(
       {
@@ -580,6 +597,7 @@ export class GroupQueue {
       resetRunState(state, groupJid);
       assertRunPhaseInvariants(state, groupJid);
       this.activeCount--;
+      this.notifyActivityChange();
       this.drainGroup(groupJid);
     }
   }
@@ -592,6 +610,7 @@ export class GroupQueue {
     assertRunPhaseInvariants(state, groupJid);
     this.activeCount++;
     this.activeTaskCount++;
+    this.notifyActivityChange();
 
     logger.info(
       {
@@ -628,6 +647,7 @@ export class GroupQueue {
       assertRunPhaseInvariants(state, groupJid);
       this.activeCount--;
       this.activeTaskCount--;
+      this.notifyActivityChange();
       this.drainGroup(groupJid);
     }
   }