fix(typing): stop keepalive restarts after run completion (land #27413, thanks @widingmarcus-cyber)

Co-authored-by: Marcus Widing <widing.marcus@gmail.com>

src/auto-reply/reply/typing.ts

@@ -99,6 +99,10 @@ export function createTypingController(params: {
     if (sealed) {
       return;
     }
+    // Late callbacks after a run completed should never restart typing.
+    if (runComplete) {
+      return;
+    }
     await onReplyStart?.();
   };