refactor: split providers into feature modules

lib/features/stats/providers/stats_providers.dart

@@ -0,0 +1,29 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../../app/error_message.dart';
+import '../../../app/load_state.dart';
+import '../../../models/stats_summary.dart';
+import '../../shared/providers/core_providers.dart';
+
+final statsProvider = NotifierProvider<StatsNotifier, LoadState<StatsSummary>>(
+  () => StatsNotifier(),
+);
+
+class StatsNotifier extends Notifier<LoadState<StatsSummary>> {
+  @override
+  LoadState<StatsSummary> build() => const LoadState.idle(StatsSummary.empty);
+
+  Future<void> load({int days = 7}) async {
+    state = LoadState.loading(state.data);
+    try {
+      final api = ref.read(apiProvider);
+      final res = await api.getStatsSummary(days: days);
+      final stats = StatsSummary.fromApi(res.data);
+      state = stats.groups.isEmpty
+          ? LoadState.empty(stats)
+          : LoadState.data(stats);
+    } catch (e) {
+      state = LoadState.error(state.data, describeLoadError(e));
+    }
+  }
+}