Add country dropdown selector to login screens of siro_service and siro_admin

siro_admin/lib/controller/auth/otp_helper.dart

@@ -23,6 +23,13 @@ class OtpHelper extends GetxController {
   static final String _checkAdminLogin =
       '${AppLink.server}/Admin/auth/login.php';
 
+  var selectedCountry = 'Jordan'.obs;
+
+  void changeCountry(String country) {
+    selectedCountry.value = country;
+    box.write(BoxName.countryCode, country);
+  }
+
   /// إرسال OTP
   static Future<bool> sendOtp(String phoneNumber) async {
     try {
@@ -281,6 +288,7 @@ class OtpHelper extends GetxController {
 
   @override
   void onInit() {
+    selectedCountry.value = box.read(BoxName.countryCode) ?? 'Jordan';
     super.onInit();
     DeviceHelper.getDeviceFingerprint().then((deviceFingerprint) {
       box.write(BoxName.fingerPrint, deviceFingerprint);