feat: add NewsItem and BriefingFeed models with tests

test/widget_test.dart

@@ -2,6 +2,8 @@ import 'package:fabled_app/data/api/voice_api.dart';
 import 'package:fabled_app/providers/voice_provider.dart';
 import 'package:fabled_app/data/models/knowledge_item.dart';
 import 'package:fabled_app/data/models/note.dart';
+import 'package:fabled_app/data/models/news_item.dart';
+import 'package:fabled_app/data/models/briefing_feed.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
@@ -146,4 +148,72 @@ void main() {
           equals('item one item two'));
     });
   });
+
+  group('NewsItem.fromJson', () {
+    test('parses all fields', () {
+      final json = {
+        'id': 42,
+        'title': 'Big news',
+        'url': 'https://example.com/article',
+        'snippet': 'A short summary.',
+        'source': 'Example News',
+        'published_at': '2026-01-15T10:00:00',
+        'topics': ['tech', 'ai'],
+        'reaction': 'up',
+      };
+      final item = NewsItem.fromJson(json);
+      expect(item.id, equals(42));
+      expect(item.title, equals('Big news'));
+      expect(item.url, equals('https://example.com/article'));
+      expect(item.snippet, equals('A short summary.'));
+      expect(item.source, equals('Example News'));
+      expect(item.publishedAt, equals(DateTime.parse('2026-01-15T10:00:00')));
+      expect(item.topics, equals(['tech', 'ai']));
+      expect(item.reaction, equals('up'));
+    });
+
+    test('handles null published_at and reaction', () {
+      final json = {
+        'id': 1,
+        'title': '',
+        'url': '',
+        'snippet': '',
+        'source': '',
+        'published_at': null,
+        'topics': <dynamic>[],
+        'reaction': null,
+      };
+      final item = NewsItem.fromJson(json);
+      expect(item.publishedAt, isNull);
+      expect(item.reaction, isNull);
+      expect(item.topics, isEmpty);
+    });
+  });
+
+  group('BriefingFeed.fromJson', () {
+    test('parses all fields', () {
+      final json = {
+        'id': 7,
+        'title': 'Hacker News',
+        'url': 'https://news.ycombinator.com/rss',
+        'category': 'tech',
+      };
+      final feed = BriefingFeed.fromJson(json);
+      expect(feed.id, equals(7));
+      expect(feed.title, equals('Hacker News'));
+      expect(feed.url, equals('https://news.ycombinator.com/rss'));
+      expect(feed.category, equals('tech'));
+    });
+
+    test('handles null category', () {
+      final json = {
+        'id': 8,
+        'title': 'Feed',
+        'url': 'https://example.com/rss',
+        'category': null,
+      };
+      final feed = BriefingFeed.fromJson(json);
+      expect(feed.category, isNull);
+    });
+  });
 }