Add safety check notification and error handling (#19055)

Adds a new app-server notification that fires when a user account has
been flagged for potential safety reasons.

codex-rs/tui/src/app/app_server_adapter.rs

@@ -400,6 +400,9 @@ fn server_notification_thread_target(
         }
         ServerNotification::ContextCompacted(notification) => Some(notification.thread_id.as_str()),
         ServerNotification::ModelRerouted(notification) => Some(notification.thread_id.as_str()),
+        ServerNotification::ModelVerification(notification) => {
+            Some(notification.thread_id.as_str())
+        }
         ServerNotification::ThreadRealtimeStarted(notification) => {
             Some(notification.thread_id.as_str())
         }