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/income/providers.dart

@@ -1,6 +1,7 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/api/api_client.dart';
+import '../../core/cache/cached.dart';
 import '../portfolio/providers.dart' show scopeProvider;
 import 'data/income_api.dart';
 
@@ -12,8 +13,8 @@ final calendarMonthsProvider = StateProvider<int>((ref) => 12);
 final calendarIncludePaidProvider = StateProvider<bool>((ref) => false);
 
 /// Доходы shares the portfolio-wide [scopeProvider]: switching the scope on Портфель must
-/// not leave the income calendar showing a different portfolio.
-final incomeCalendarProvider = FutureProvider.autoDispose<IncomeCalendar>((ref) async {
+/// not leave the income calendar showing a different portfolio. See `docs/ai/offline-cache.md`.
+final incomeCalendarProvider = FutureProvider.autoDispose<Cached<IncomeCalendar>>((ref) async {
   final scope = ref.watch(scopeProvider);
   final months = ref.watch(calendarMonthsProvider);
   final includePaid = ref.watch(calendarIncludePaidProvider);
@@ -29,7 +30,7 @@ final incomeCalendarProvider = FutureProvider.autoDispose<IncomeCalendar>((ref)
 /// How far the history goes back, in months.
 final historyMonthsProvider = StateProvider<int>((ref) => 24);
 
-final incomeHistoryProvider = FutureProvider.autoDispose<IncomeHistory>((ref) async {
+final incomeHistoryProvider = FutureProvider.autoDispose<Cached<IncomeHistory>>((ref) async {
   final scope = ref.watch(scopeProvider);
   final months = ref.watch(historyMonthsProvider);
   final now = DateTime.now();
@@ -42,7 +43,7 @@ final incomeHistoryProvider = FutureProvider.autoDispose<IncomeHistory>((ref) as
 
 final forecastMonthsProvider = StateProvider<int>((ref) => 12);
 
-final incomeForecastProvider = FutureProvider.autoDispose<IncomeForecast>((ref) async {
+final incomeForecastProvider = FutureProvider.autoDispose<Cached<IncomeForecast>>((ref) async {
   final scope = ref.watch(scopeProvider);
   return ref
       .watch(incomeApiProvider)