feat: make core pages local-first offline

frontend/lib/features/home/pages/home_page.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 import 'package:miaoji_zhang/shared/api/api_client.dart';
@@ -10,6 +12,7 @@ import 'package:miaoji_zhang/shared/theme/app_theme.dart';
 import 'package:miaoji_zhang/shared/widgets/category_icon.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/features/home/pages/tx_detail_page.dart';
 import 'package:miaoji_zhang/features/home/pages/ledger_sheet.dart';
 import 'package:miaoji_zhang/shared/services/shanghai_time.dart';
@@ -28,6 +31,7 @@ class HomePageState extends State<HomePage> {
   bool _loading = true;
   String? _error;
   late DateTime _month;
+  int _loadRevision = 0;
 
   @override
   void initState() {
@@ -36,7 +40,7 @@ class HomePageState extends State<HomePage> {
     PublicConfigApi.companionNotifier.addListener(_refreshCompanion);
     TransactionEvents.revision.addListener(_refreshTransactions);
     CurrentLedgerStore.instance.addListener(_refreshLedger);
-    refresh();
+    unawaited(refresh());
   }
 
   void _refreshCompanion() {
@@ -60,33 +64,56 @@ class HomePageState extends State<HomePage> {
   }
 
   Future<void> refresh() async {
+    final revision = ++_loadRevision;
     setState(() {
       _loading = true;
       _error = null;
     });
     try {
-      await CurrentLedgerStore.instance.ensureLoaded();
-      final results = await Future.wait<dynamic>([
-        TxApi.month(_month.year, _month.month),
-        BudgetApi.get(_month.year, _month.month),
-      ]);
-      if (mounted) {
+      await CurrentLedgerStore.instance.loadCached();
+      final localSummary = TxApi.monthLocal(_month.year, _month.month);
+      final localBudgets = BudgetApi.getLocal(_month.year, _month.month);
+      if (mounted && revision == _loadRevision) {
         setState(() {
-          _summary = results[0] as MonthSummary;
-          _budgets = results[1] as BudgetsData;
+          _summary = localSummary;
+          _budgets = localBudgets;
         });
       }
     } catch (error) {
-      try {
-        final summary = await TxApi.month(_month.year, _month.month);
-        if (mounted) setState(() => _summary = summary);
-      } catch (fallbackError) {
-        if (mounted) {
-          setState(() => _error = apiErrorMessage(fallbackError));
-        }
+      if (mounted && revision == _loadRevision) {
+        setState(() {
+          _error = apiErrorMessage(error);
+          _loading = false;
+        });
       }
-    } finally {
-      if (mounted) setState(() => _loading = false);
+      return;
+    }
+
+    await Future.wait([
+      () async {
+        try {
+          await CurrentLedgerStore.instance.refreshRemote();
+        } catch (_) {}
+      }(),
+      () async {
+        try {
+          final summary = await TxApi.monthRemote(_month.year, _month.month);
+          if (mounted && revision == _loadRevision) {
+            setState(() => _summary = summary);
+          }
+        } catch (_) {}
+      }(),
+      () async {
+        try {
+          final budgets = await BudgetApi.getRemote(_month.year, _month.month);
+          if (mounted && revision == _loadRevision) {
+            setState(() => _budgets = budgets);
+          }
+        } catch (_) {}
+      }(),
+    ]);
+    if (mounted && revision == _loadRevision) {
+      setState(() => _loading = false);
     }
   }
 
@@ -175,6 +202,7 @@ class HomePageState extends State<HomePage> {
                       ),
                     ),
                     Spacer(),
+                    BackendStatusIcon(onRetry: refresh),
                     IconButton(
                       icon: AppIcons.icon(
                         AppIcons.search,