feat: make core pages local-first offline

frontend/lib/features/stats/report_page.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:miaoji_zhang/shared/api/api_client.dart';
 import 'package:miaoji_zhang/shared/api/business_api.dart';
@@ -6,6 +8,7 @@ import 'package:miaoji_zhang/shared/services/current_ledger_store.dart';
 import 'package:miaoji_zhang/shared/theme/app_theme.dart';
 import 'package:miaoji_zhang/shared/widgets/app_icons.dart';
 import 'package:miaoji_zhang/shared/widgets/async_error_view.dart';
+import 'package:miaoji_zhang/shared/widgets/backend_status_icon.dart';
 import 'package:miaoji_zhang/shared/widgets/category_icon.dart';
 import 'package:miaoji_zhang/shared/services/shanghai_time.dart';
 import 'package:miaoji_zhang/shared/services/session_store.dart';
@@ -25,13 +28,14 @@ class _ReportPageState extends State<ReportPage> {
   String? _error;
   DateTime _anchor = ShanghaiTime.now;
   _ReportKind _kind = _ReportKind.monthly;
+  int _loadRevision = 0;
 
   @override
   void initState() {
     super.initState();
     PublicConfigApi.companionNotifier.addListener(_refreshCompanion);
     CurrentLedgerStore.instance.addListener(_load);
-    _load();
+    unawaited(_load());
   }
 
   @override
@@ -46,24 +50,33 @@ class _ReportPageState extends State<ReportPage> {
   }
 
   Future<void> _load() async {
+    final revision = ++_loadRevision;
     setState(() {
       _loading = true;
       _error = null;
     });
     try {
-      final report = switch (_kind) {
-        _ReportKind.weekly => await ReportApi.weekly(_anchor),
-        _ReportKind.monthly => await ReportApi.monthlyPeriod(
-          _anchor.year,
-          _anchor.month,
-        ),
-        _ReportKind.yearly => await ReportApi.yearly(_anchor.year),
+      final period = switch (_kind) {
+        _ReportKind.weekly => 'week',
+        _ReportKind.monthly => 'month',
+        _ReportKind.yearly => 'year',
       };
-      if (mounted) setState(() => _report = report);
+      final local = ReportApi.local(period, _anchor);
+      if (mounted && revision == _loadRevision) {
+        setState(() => _report = local);
+      }
+      final remote = await ReportApi.remote(period, _anchor);
+      if (mounted && revision == _loadRevision) {
+        setState(() => _report = remote);
+      }
     } catch (error) {
-      if (mounted) setState(() => _error = apiErrorMessage(error));
+      if (mounted && revision == _loadRevision && _report == null) {
+        setState(() => _error = apiErrorMessage(error));
+      }
     } finally {
-      if (mounted) setState(() => _loading = false);
+      if (mounted && revision == _loadRevision) {
+        setState(() => _loading = false);
+      }
     }
   }
 
@@ -108,6 +121,7 @@ class _ReportPageState extends State<ReportPage> {
     return Scaffold(
       appBar: AppBar(
         title: Text(SessionStore.instance.aiEnabled ? 'AI 报告' : '报告'),
+        actions: [BackendStatusIcon(onRetry: _load)],
       ),
       body: Column(
         children: [