fix：持仓详情编辑，资讯下拉加载更多

lib/features/news/application/news_controller.dart

@@ -8,10 +8,17 @@ final newsControllerProvider = StateNotifierProvider<NewsController, NewsState>(
 );
 
 class NewsState {
-  const NewsState({required this.items, required this.refreshedAt});
+  const NewsState({
+    required this.items,
+    required this.refreshedAt,
+    required this.hasMore,
+    required this.loadingMore,
+  });
 
   final List<NewsItem> items;
   final DateTime refreshedAt;
+  final bool hasMore;
+  final bool loadingMore;
 }
 
 class NewsController extends StateNotifier<NewsState> {
@@ -20,15 +27,42 @@ class NewsController extends StateNotifier<NewsState> {
         NewsState(
           items: _repository.loadFeed(),
           refreshedAt: DateTime(2026, 6, 18, 16, 11),
+          hasMore: true,
+          loadingMore: false,
         ),
       );
 
   final MockNewsRepository _repository;
+  static const _pageSize = 3;
 
   void refresh() {
+    final items = _repository.loadFeed(limit: _pageSize);
     state = NewsState(
-      items: _repository.loadFeed(),
+      items: items,
       refreshedAt: DateTime.now(),
+      hasMore: items.length == _pageSize,
+      loadingMore: false,
     );
   }
+
+  bool loadMore() {
+    if (state.loadingMore || !state.hasMore) return state.hasMore;
+    state = NewsState(
+      items: state.items,
+      refreshedAt: state.refreshedAt,
+      hasMore: state.hasMore,
+      loadingMore: true,
+    );
+    final next = _repository.loadFeed(
+      offset: state.items.length,
+      limit: _pageSize,
+    );
+    state = NewsState(
+      items: [...state.items, ...next],
+      refreshedAt: state.refreshedAt,
+      hasMore: next.length == _pageSize,
+      loadingMore: false,
+    );
+    return state.hasMore;
+  }
 }