Set persistant WiFi opmode to WIFI_OFF if not already configured that way

lib/framework/WiFiSettingsService.cpp

@@ -1,6 +1,12 @@
 #include <WiFiSettingsService.h>
 
 WiFiSettingsService::WiFiSettingsService(AsyncWebServer* server, FS* fs, SecurityManager* securityManager) : AdminSettingsService(server, fs, securityManager, WIFI_SETTINGS_SERVICE_PATH, WIFI_SETTINGS_FILE) {
+  // We want the device to come up in opmode=0 (WIFI_OFF), when erasing the flash this is not the default.
+  // If needed, we save opmode=0 before disabling persistence so the device boots with WiFi disabled in the future.
+  if (WiFi.getMode() != WIFI_OFF) {
+    WiFi.mode(WIFI_OFF);  
+  }
+  
   // Disable WiFi config persistance and auto reconnect
   WiFi.persistent(false);
   WiFi.setAutoReconnect(false);