refactor(ads): simplify NativeAd model

- Remove common native ad fields from the model
- Keep only the essential adObject field
- Update class documentation to reflect changes

Author: fulleni

lib/ads/models/native_ad.dart

@@ -5,57 +5,20 @@ import 'package:flutter/foundation.dart';
 /// A generic, provider-agnostic model representing a native advertisement.
 ///
 /// This model decouples the application's core logic from specific ad network
-/// SDKs (e.g., Google Mobile Ads). It contains common fields found in native
-/// ads and holds a reference to the original, SDK-specific ad object for
-/// rendering purposes.
+/// SDKs (e.g., Google Mobile Ads). It holds a reference to the original,
+/// SDK-specific ad object for rendering purposes.
 /// {@endtemplate}
 @immutable
 class NativeAd extends Equatable {
   /// {@macro native_ad}
   const NativeAd({
     required this.id,
-    required this.headline,
-    required this.body,
-    required this.callToAction,
-    this.iconUrl,
-    this.imageUrl,
-    this.advertiser,
-    this.starRating,
-    this.store,
-    this.price,
     required this.adObject,
   });
 
   /// A unique identifier for this specific native ad instance.
   final String id;
 
-  /// The main headline or title of the advertisement.
-  final String headline;
-
-  /// The main body text or description of the advertisement.
-  final String body;
-
-  /// The text for the call-to-action button (e.g., "Install", "Learn More").
-  final String callToAction;
-
-  /// The URL of the ad's icon image (e.g., app icon).
-  final String? iconUrl;
-
-  /// The URL of the main image asset for the ad.
-  final String? imageUrl;
-
-  /// The name of the advertiser or sponsor.
-  final String? advertiser;
-
-  /// The star rating for the advertised app (typically 1.0 to 5.0).
-  final double? starRating;
-
-  /// The name of the app store (e.g., "Google Play", "App Store").
-  final String? store;
-
-  /// The price of the advertised app or product.
-  final String? price;
-
   /// The original, SDK-specific ad object.
   ///
   /// This object is passed directly to the ad network's UI widget for rendering.
@@ -66,15 +29,6 @@ class NativeAd extends Equatable {
   @override
   List<Object?> get props => [
         id,
-        headline,
-        body,
-        callToAction,
-        iconUrl,
-        imageUrl,
-        advertiser,
-        starRating,
-        store,
-        price,
         adObject,
       ];
 }