feat(app): offline-кэш на остальных экранах — фаза 5

accounts, cashflow, categories, goals, income, portfolio (+instrument),
rebalance, tax, rules переведены на Cached<T> по контракту
docs/ai/offline-cache.md. Общие/второстепенные селекторы (scopesProvider,
categoriesListProvider и т.п.) оставлены как есть — не основной контент
экрана. sync_page.dart и settings_page.dart не тронуты (первый — заменён
health-page отдельно, второй — чистые действия без списка для баннера).

app/lib/features/goals/data/goals_api.dart

@@ -11,6 +11,7 @@ library;
 
 import 'package:dio/dio.dart';
 
+import '../../../core/cache/cached.dart';
 import '../../../core/utils/json.dart';
 
 class Goal {
@@ -125,11 +126,14 @@ class GoalsApi {
 
   static const _base = '/api/v1/goals';
 
-  Future<List<Goal>> list() async {
+  /// See `docs/ai/offline-cache.md`: this hand-written client returns `Cached<T>` directly
+  /// (there is no generated `Response<T>` for `GoalsPage` to unwrap `r.cached` from).
+  Future<Cached<List<Goal>>> list() async {
     final r = await _dio.get<List<dynamic>>(_base);
-    return (r.data ?? const [])
+    final goals = (r.data ?? const [])
         .map((e) => Goal.fromJson(Map<String, dynamic>.from(e as Map)))
         .toList();
+    return Cached(goals, fetchedAt: r.extra['fetchedAt'] as DateTime?);
   }
 
   Future<Goal> create(Goal goal) async {
@@ -144,8 +148,11 @@ class GoalsApi {
 
   Future<void> delete(int id) => _dio.delete<void>('$_base/$id');
 
-  Future<GoalProgress> progress(int id) async {
+  Future<Cached<GoalProgress>> progress(int id) async {
     final r = await _dio.get<Map<String, dynamic>>('$_base/$id/progress');
-    return GoalProgress.fromJson(r.data ?? const {});
+    return Cached(
+      GoalProgress.fromJson(r.data ?? const {}),
+      fetchedAt: r.extra['fetchedAt'] as DateTime?,
+    );
   }
 }

app/lib/features/goals/goal_card.dart

@@ -86,7 +86,7 @@ class GoalCard extends ConsumerWidget {
             AsyncValueView(
               value: progress,
               onRetry: () => ref.invalidate(goalProgressProvider(goal.id)),
-              data: (p) => GoalProgressView(goal: goal, progress: p),
+              data: (cached) => GoalProgressView(goal: goal, progress: cached.data),
             ),
           ],
         ),

app/lib/features/goals/goals_page.dart

@@ -1,9 +1,11 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/cache/cached.dart';
 import '../../core/utils/json.dart';
 import '../../core/widgets/async_value_view.dart';
 import '../../core/widgets/empty_state.dart';
+import '../../core/widgets/stale_banner.dart';
 import 'data/goals_api.dart';
 import 'goal_card.dart';
 import 'goal_edit_dialog.dart';
@@ -78,6 +80,13 @@ class _GoalsPageState extends ConsumerState<GoalsPage> {
   @override
   Widget build(BuildContext context) {
     final goals = ref.watch(goalsProvider);
+    // Every card's own progress fetch counts toward the one banner too — a fresh list with a
+    // stale progress card is still an offline dashboard, just not a visibly empty one.
+    final goalIds = [for (final g in goals.valueOrNull?.data ?? const <Goal>[]) g.id];
+    final stale = oldestFetch([
+      goals.valueOrNull?.fetchedAt,
+      for (final id in goalIds) ref.watch(goalProgressProvider(id)).valueOrNull?.fetchedAt,
+    ]);
 
     return Scaffold(
       appBar: AppBar(
@@ -105,12 +114,14 @@ class _GoalsPageState extends ConsumerState<GoalsPage> {
         child: AsyncValueView(
           value: goals,
           onRetry: () => ref.invalidate(goalsProvider),
-          data: (all) {
+          data: (cached) {
+            final all = cached.data;
             final rows = _showArchived ? all : all.where((g) => !g.archived).toList();
             if (rows.isEmpty) {
               return ListView(
                 padding: const EdgeInsets.all(16),
                 children: [
+                  if (stale != null) StaleBanner(fetchedAt: stale),
                   const SizedBox(height: 48),
                   EmptyState(
                     icon: Icons.flag_outlined,
@@ -125,6 +136,7 @@ class _GoalsPageState extends ConsumerState<GoalsPage> {
             return ListView(
               padding: const EdgeInsets.fromLTRB(16, 16, 16, 88),
               children: [
+                if (stale != null) StaleBanner(fetchedAt: stale),
                 for (final g in rows)
                   Padding(
                     padding: const EdgeInsets.only(bottom: 12),

app/lib/features/goals/providers.dart

@@ -1,17 +1,19 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/api/api_client.dart';
+import '../../core/cache/cached.dart';
 import 'data/goals_api.dart';
 
 final goalsApiProvider = Provider<GoalsApi>((ref) => GoalsApi(ref.watch(apiProvider).dio));
 
+/// See `docs/ai/offline-cache.md`.
 final goalsProvider =
-    FutureProvider.autoDispose<List<Goal>>((ref) => ref.watch(goalsApiProvider).list());
+    FutureProvider.autoDispose<Cached<List<Goal>>>((ref) => ref.watch(goalsApiProvider).list());
 
 /// Progress is computed server-side and refetched per goal — the client never projects
 /// anything itself.
 final goalProgressProvider =
-    FutureProvider.autoDispose.family<GoalProgress, int>((ref, id) async {
+    FutureProvider.autoDispose.family<Cached<GoalProgress>, int>((ref, id) async {
   return ref.watch(goalsApiProvider).progress(id);
 });