esp32 improvements

- better clock seconds
- better alarm (image before audio, supposedly)

components/audio_client/audio_client.h

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <stdbool.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
 #include "lvgl.h"
 
 #ifdef __cplusplus
@@ -30,6 +32,12 @@ void audio_client_stop(void);
 /** Get current audio client state. */
 audio_state_t audio_client_get_state(void);
 
+/**
+ * Register a task to be notified (via xTaskNotifyGive) when a new status
+ * image arrives.  Call before audio_client_start().
+ */
+void audio_client_set_image_notify_task(TaskHandle_t task);
+
 /**
  * Get the latest status image descriptor.
  * @param updated  Set to true if a new image arrived since last call, then reset.