fix(subagents): announce delivery with descendant gating, frozen result refresh, and cron retry (#35080)

Thanks @tyler6204

src/agents/subagent-registry-runtime.ts

@@ -3,5 +3,8 @@ export {
   countPendingDescendantRuns,
   countPendingDescendantRunsExcludingRun,
   isSubagentSessionRunActive,
+  listSubagentRunsForRequester,
+  replaceSubagentRunAfterSteer,
   resolveRequesterForChildSession,
+  shouldIgnorePostCompletionAnnounceForSession,
 } from "./subagent-registry.js";