feat(app): 搜索改为调用后端并渲染卡片结果

lib/core/data/repositories/search_repository.dart

@@ -0,0 +1,26 @@
+// Author: fruit.com.cn
+
+import '../models/search_result.dart';
+import '../remote/catalog_api.dart';
+
+/// 搜索数据来源：只调用后端 `/app/search`，不在客户端做本地过滤。
+abstract interface class SearchRepository {
+  Future<SearchResult> search(
+    String keyword, {
+    int pageIndex = 1,
+    int pageSize = 20,
+  });
+}
+
+class HttpSearchRepository implements SearchRepository {
+  const HttpSearchRepository(this._api);
+
+  final CatalogApi _api;
+
+  @override
+  Future<SearchResult> search(
+    String keyword, {
+    int pageIndex = 1,
+    int pageSize = 20,
+  }) => _api.search(keyword, pageIndex: pageIndex, pageSize: pageSize);
+}