Gate realtime audio interruption logic to v2 (#14984)

- thread the realtime version into conversation start and app-server
notifications
- keep playback-aware mic gating and playback interruption behavior on
v2 only, leaving v1 on the legacy path

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

@@ -492,6 +492,7 @@ fn server_notification_thread_events(
                 id: String::new(),
                 msg: EventMsg::RealtimeConversationStarted(RealtimeConversationStartedEvent {
                     session_id: notification.session_id,
+                    version: notification.version,
                 }),
             }],
         )),