chore: prepare yanting monorepo handoff

lib/data/api/report_data_source.dart

@@ -0,0 +1,77 @@
+import 'dart:convert';
+
+import 'package:http/http.dart' as http;
+
+import '../models/models.dart';
+
+abstract class ReportDataSource {
+  Future<List<ReportCardModel>> recommended();
+  Future<List<ReportCardModel>> reports();
+  Future<List<Institution>> institutions();
+  Future<Institution> institutionDetail(String institutionId);
+  Future<List<AudioItem>> listen();
+  Future<ReportDetail> reportDetail(String reportId);
+  Future<ModuleDetail> moduleDetail(String reportId, String moduleId);
+}
+
+class RnbApiDataSource implements ReportDataSource {
+  RnbApiDataSource({
+    http.Client? client,
+    this.baseUrl = const String.fromEnvironment('RNB_API_BASE'),
+  }) : client = client ?? http.Client();
+
+  final http.Client client;
+  final String baseUrl;
+
+  Future<JsonMap> _get(String path) async {
+    if (baseUrl.isEmpty) {
+      throw StateError('RNB_API_BASE is required for live API requests.');
+    }
+    final response = await client.get(Uri.parse('$baseUrl$path'));
+    if (response.statusCode != 200) {
+      throw StateError('Request failed: ${response.statusCode}');
+    }
+    return jsonDecode(utf8.decode(response.bodyBytes)) as JsonMap;
+  }
+
+  List<JsonMap> _items(JsonMap body) => asMapList(body['items']);
+
+  @override
+  Future<List<ReportCardModel>> recommended() async {
+    final body = await _get('/feed/recommended');
+    return _items(body).map(ReportCardModel.fromJson).toList();
+  }
+
+  @override
+  Future<List<ReportCardModel>> reports() async {
+    final body = await _get('/reports');
+    return _items(body).map(ReportCardModel.fromJson).toList();
+  }
+
+  @override
+  Future<List<Institution>> institutions() async {
+    final body = await _get('/institutions');
+    return _items(body).map(Institution.fromJson).toList();
+  }
+
+  @override
+  Future<Institution> institutionDetail(String institutionId) async {
+    return Institution.fromJson(await _get('/institutions/$institutionId'));
+  }
+
+  @override
+  Future<List<AudioItem>> listen() async {
+    final body = await _get('/listen');
+    return _items(body).map(AudioItem.fromJson).toList();
+  }
+
+  @override
+  Future<ReportDetail> reportDetail(String reportId) async {
+    return ReportDetail.fromJson(await _get('/reports/$reportId'));
+  }
+
+  @override
+  Future<ModuleDetail> moduleDetail(String reportId, String moduleId) async {
+    return ModuleDetail.fromJson(await _get('/reports/$reportId/modules/$moduleId'));
+  }
+}