add stats page

lib/services/api_service.dart

@@ -128,7 +128,12 @@ class ApiService {
       await _onUnauthorized!();
     }
 
-    throw Exception('API error ${res.statusCode}: $body');
+    final message = _extractErrorMessage(body);
+    throw ApiException(
+      statusCode: res.statusCode,
+      message: message,
+      body: body,
+    );
   }
 
   dynamic _decodeBody(http.Response res) {
@@ -149,4 +154,41 @@ class ApiService {
       return res.body;
     }
   }
+
+  String _extractErrorMessage(dynamic body) {
+    if (body == null) return 'No response body';
+    if (body is String) return body;
+    if (body is Map<String, dynamic>) {
+      for (final key in ['message', 'error', 'detail', 'msg']) {
+        final val = body[key];
+        if (val is String && val.trim().isNotEmpty) return val;
+      }
+      return body.toString();
+    }
+    if (body is List) {
+      final parts = body
+          .map((e) => e is Map
+              ? _extractErrorMessage(Map<String, dynamic>.from(e))
+              : e.toString())
+          .where((e) => e.trim().isNotEmpty)
+          .toList();
+      if (parts.isNotEmpty) return parts.join('; ');
+    }
+    return body.toString();
+  }
+}
+
+class ApiException implements Exception {
+  final int statusCode;
+  final String message;
+  final dynamic body;
+
+  ApiException({
+    required this.statusCode,
+    required this.message,
+    this.body,
+  });
+
+  @override
+  String toString() => 'API error $statusCode: $message';
 }

lib/services/data_service/data_service.dart

@@ -11,3 +11,4 @@ part 'data_service_traction.dart';
 part 'data_service_trips.dart';
 part 'data_service_notifications.dart';
 part 'data_service_badges.dart';
+part 'data_service_stats.dart';

lib/services/data_service/data_service_core.dart

@@ -28,6 +28,10 @@ class DataService extends ChangeNotifier {
   // Homepage Data
   HomepageStats? _homepageStats;
   HomepageStats? get homepageStats => _homepageStats;
+  StatsAbout? _aboutStats;
+  StatsAbout? get aboutStats => _aboutStats;
+  bool _isAboutStatsLoading = false;
+  bool get isAboutStatsLoading => _isAboutStatsLoading;
 
   // Legs Data
   List<Leg> _legs = [];

lib/services/data_service/data_service_stats.dart

@@ -0,0 +1,28 @@
+part of 'data_service.dart';
+
+extension DataServiceStats on DataService {
+  Future<void> fetchAboutStats({bool force = false}) async {
+    if (_isAboutStatsLoading) return;
+    if (!force && _aboutStats != null) return;
+    _isAboutStatsLoading = true;
+    _notifyAsync();
+    try {
+      final json = await api.get('/stats/about');
+      if (json is Map<String, dynamic>) {
+        _aboutStats = StatsAbout.fromJson(json);
+      } else if (json is Map) {
+        _aboutStats = StatsAbout.fromJson(
+          json.map((key, value) => MapEntry(key.toString(), value)),
+        );
+      } else {
+        throw Exception('Unexpected stats response: $json');
+      }
+    } catch (e) {
+      debugPrint('Failed to fetch about stats: $e');
+      _aboutStats = null;
+    } finally {
+      _isAboutStatsLoading = false;
+      _notifyAsync();
+    }
+  }
+}