Add ESP32 OTA rollback support

mongoose.c

@@ -10330,7 +10330,7 @@ void mg_ota_poll(struct mg_mgr *mgr) {
   static uint64_t t = 5000;  // Fire first time 5 sec after boot
 
   static uint64_t feed_timer;  // Advances 500ms per tick; tracks elapsed time
-  if (MG_OTA_STATE_GET() == MG_OTA_TESTING &&
+  if (MG_OTA_STATE_GET() == MG_OTA_FAILED &&
       mg_timer_expired(&feed_timer, 500, mg_millis())) {
     if (feed_timer < (uint64_t) MG_OTA_ROLLBACK_TIMEOUT_SECONDS * 1000) {
       MG_OTA_ROLLBACK_TIMER_FEED();  // Feed watchdog every 500ms
@@ -10537,6 +10537,10 @@ bool mg_ota_end(void) {
   }
   MG_DEBUG(("Finished ESP32 OTA, success: %d", s_ota_success));
   s_ota_update_partition = NULL;
+  if (s_ota_success) {
+    MG_OTA_STATE_SET(MG_OTA_TESTING);
+    esp_restart();
+  }
   return s_ota_success;
 }