add sening functions

wangzhibo

2026-08-26 70481429367ca00144b24f118cbfdfb28b02967d

 xiaozhi-esp32-2.2.6/main/audio/audio_service.h

@@ -78,6 +78,7 @@
struct AudioServiceCallbacks {
    std::function<void(void)> on_send_queue_available;
    std::function<void(const std::string&)> on_wake_word_detected;
    std::function<void(const std::string&)> on_offline_command_detected;
    std::function<void(bool)> on_vad_change;
    std::function<void(void)> on_audio_testing_queue_full;
};