made the city search functional

lib/models/offers_and_discounts/wala_plus_city_model.dart

@@ -0,0 +1,51 @@
+class WalaPlusCityModel {
+  int? cityId;
+  String? cityNameAr;
+  String? cityNameEn;
+  String? countryNameAr;
+  String? countryNameEn;
+
+  WalaPlusCityModel({
+    this.cityId,
+    this.cityNameAr,
+    this.cityNameEn,
+    this.countryNameAr,
+    this.countryNameEn,
+  });
+
+  factory WalaPlusCityModel.fromJson(Map<String, dynamic> json) {
+    return WalaPlusCityModel(
+      cityId:
+          json['city_id'] is int
+              ? json['city_id']
+              : int.tryParse(json['city_id']?.toString() ?? ''),
+      cityNameAr: json['city_name_ar']?.toString(),
+      cityNameEn: json['city_name_en']?.toString(),
+      countryNameAr: json['country_name_ar']?.toString(),
+      countryNameEn: json['country_name_en']?.toString(),
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'city_id': cityId,
+      'city_name_ar': cityNameAr,
+      'city_name_en': cityNameEn,
+      'country_name_ar': countryNameAr,
+      'country_name_en': countryNameEn,
+    };
+  }
+
+  String getDisplayName(bool isAr) {
+    String? primary = isAr ? cityNameAr : cityNameEn;
+    if (primary != null && primary.trim().isNotEmpty) return primary.trim();
+    String? fallback = isAr ? cityNameEn : cityNameAr;
+    return fallback?.trim() ?? '';
+  }
+
+  bool get isAllCities {
+    String en = (cityNameEn ?? '').trim().toLowerCase();
+    String ar = (cityNameAr ?? '').trim();
+    return en == 'all cities' || ar == 'جميع المدن';
+  }
+}