feat(app): offline-кэш GET-запросов на дашборде — фаза 5

CacheInterceptor кэширует каждый успешный GET по путь+параметры в drift
(sqlite нативно, wasm+OPFS в браузере) и подменяет им сетевую ошибку;
провайдер отдаёт Cached<T>, экран показывает баннер «данные на …».
Контракт для остальных экранов — docs/ai/offline-cache.md.

flake.nix: libsecret/pkg-config для линуксовой сборки, jq/curl для
just app-web-assets (сборка sqlite3.wasm + drift_worker.js).

app/lib/features/home/home_page.dart

@@ -7,11 +7,13 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../core/auth/auth_controller.dart';
+import '../../core/cache/cached.dart';
 import '../../core/theme/chart_colors.dart';
 import '../../core/utils/ru_date.dart';
 import '../../core/widgets/async_value_view.dart';
 import '../../core/widgets/empty_state.dart';
 import '../../core/widgets/money_text.dart';
+import '../../core/widgets/stale_banner.dart';
 import '../../core/api/api_client.dart';
 import 'providers.dart';
 
@@ -109,6 +111,17 @@ class _HomePageState extends ConsumerState<HomePage> {
     final dataQuality = ref.watch(dataQualityProvider);
     final portfolio = ref.watch(portfolioSummaryHomeProvider);
 
+    final stale = oldestFetch([
+      breakdown.valueOrNull?.fetchedAt,
+      series.valueOrNull?.fetchedAt,
+      thisMonth.valueOrNull?.fetchedAt,
+      last12.valueOrNull?.fetchedAt,
+      runway.valueOrNull?.fetchedAt,
+      status.valueOrNull?.fetchedAt,
+      dataQuality.valueOrNull?.fetchedAt,
+      portfolio.valueOrNull?.fetchedAt,
+    ]);
+
     return Scaffold(
       appBar: AppBar(
         title: const Text('Обзор'),
@@ -128,13 +141,15 @@ class _HomePageState extends ConsumerState<HomePage> {
         child: ListView(
           padding: const EdgeInsets.all(16),
           children: [
+            if (stale != null) StaleBanner(fetchedAt: stale),
             Row(
               children: [
                 Expanded(
                   child: AsyncValueView(
                     value: status,
                     onRetry: () => ref.invalidate(metricsStatusProvider),
-                    data: (log) {
+                    data: (cached) {
+                      final log = cached.data;
                       final at = log?.finishedAt ?? log?.startedAt;
                       final text = at == null
                           ? 'Данные ещё не пересчитывались'
@@ -145,15 +160,18 @@ class _HomePageState extends ConsumerState<HomePage> {
                 ),
                 AsyncValueView(
                   value: dataQuality,
-                  data: (rows) => ActionChip(
-                    avatar: Icon(
-                      rows.isEmpty ? Icons.check_circle_outline : Icons.warning_amber_outlined,
-                      size: 18,
-                      color: rows.isEmpty ? Colors.green : _severityColor(rows.first.severity),
-                    ),
-                    label: Text(rows.isEmpty ? 'ок' : '${rows.length} замечаний'),
-                    onPressed: rows.isEmpty ? null : () => _showDataQuality(rows),
-                  ),
+                  data: (cached) {
+                    final rows = cached.data;
+                    return ActionChip(
+                      avatar: Icon(
+                        rows.isEmpty ? Icons.check_circle_outline : Icons.warning_amber_outlined,
+                        size: 18,
+                        color: rows.isEmpty ? Colors.green : _severityColor(rows.first.severity),
+                      ),
+                      label: Text(rows.isEmpty ? 'ок' : '${rows.length} замечаний'),
+                      onPressed: rows.isEmpty ? null : () => _showDataQuality(rows),
+                    );
+                  },
                 ),
               ],
             ),
@@ -161,7 +179,7 @@ class _HomePageState extends ConsumerState<HomePage> {
             AsyncValueView(
               value: breakdown,
               onRetry: () => ref.invalidate(netWorthBreakdownProvider),
-              data: (b) => _NetWorthTiles(breakdown: b),
+              data: (cached) => _NetWorthTiles(breakdown: cached.data),
             ),
             const SizedBox(height: 12),
             Row(
@@ -170,7 +188,7 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: thisMonth,
                     onRetry: () => ref.invalidate(cashflowThisMonthProvider),
-                    data: (m) => _MonthTiles(month: m),
+                    data: (cached) => _MonthTiles(month: cached.data),
                   ),
                 ),
               ],
@@ -179,13 +197,14 @@ class _HomePageState extends ConsumerState<HomePage> {
             AsyncValueView(
               value: portfolio,
               onRetry: () => ref.invalidate(portfolioSummaryHomeProvider),
-              data: (s) => s == null ? const SizedBox.shrink() : _PortfolioTiles(summary: s),
+              data: (cached) =>
+                  cached.data == null ? const SizedBox.shrink() : _PortfolioTiles(summary: cached.data!),
             ),
             const SizedBox(height: 12),
             AsyncValueView(
               value: runway,
               onRetry: () => ref.invalidate(runwayProvider),
-              data: (r) => _RunwayTile(runway: r),
+              data: (cached) => _RunwayTile(runway: cached.data),
             ),
             const SizedBox(height: 24),
             LayoutBuilder(
@@ -196,9 +215,9 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: series,
                     onRetry: () => ref.invalidate(netWorthSeriesProvider),
-                    data: (rows) => rows.isEmpty
+                    data: (cached) => cached.data.isEmpty
                         ? const EmptyState(icon: Icons.show_chart, message: 'Пока нет данных.')
-                        : _NetWorthChart(rows: rows),
+                        : _NetWorthChart(rows: cached.data),
                   ),
                 );
                 final cashflowChart = _ChartCard(
@@ -206,9 +225,9 @@ class _HomePageState extends ConsumerState<HomePage> {
                   child: AsyncValueView(
                     value: last12,
                     onRetry: () => ref.invalidate(cashflowLast12Provider),
-                    data: (rows) => rows.isEmpty
+                    data: (cached) => cached.data.isEmpty
                         ? const EmptyState(icon: Icons.bar_chart, message: 'Пока нет данных.')
-                        : _IncomeExpenseChart(rows: rows),
+                        : _IncomeExpenseChart(rows: cached.data),
                   ),
                 );
                 if (wide) {