fix: close task container promptly when agent uses IPC-only messaging (#840)

Scheduled tasks that send messages via send_message (IPC) instead of
returning text as result left the container idle for ~30 minutes until
the hard timeout killed it (exit 137). This blocked new messages for
the group during that window.

Root cause: scheduleClose() was only called inside the
`if (streamedOutput.result)` branch. Tasks that communicate solely
through IPC (e.g. heartbeat check-ins) complete with result=null,
so the 10s close timer was never set.

Fix: also call scheduleClose() on status==='success', covering both
result-based and IPC-only task completions.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/task-scheduler.ts

@@ -191,6 +191,7 @@ async function runTask(
         }
         if (streamedOutput.status === 'success') {
           deps.queue.notifyIdle(task.chat_jid);
+          scheduleClose(); // Close promptly even when result is null (e.g. IPC-only tasks)
         }
         if (streamedOutput.status === 'error') {
           error = streamedOutput.error || 'Unknown error';