feat(app): экраны импорта отчётов, целей, доходов, ребалансировки, налогов и бенчмарков

Импорт (/imports, /instruments/pending) и фаза 4 (/goals, /income,
/rebalance, /tax, аналитика-хаб с benchmarks_card) — по
docs/ai/import-contract.md и docs/ai/phase4-contract.md. file_picker для
загрузки отчёта.

app/lib/features/imports/providers.dart

@@ -0,0 +1,35 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../core/api/api_client.dart';
+import '../events/providers.dart';
+import '../home/providers.dart';
+import '../portfolio/providers.dart';
+import 'data/imports_api.dart';
+
+final importsApiProvider = Provider<ImportsApi>((ref) => ImportsApi(ref.watch(apiProvider).dio));
+
+/// The list on `/imports`. Not auto-disposed by status: the filter is a separate provider so
+/// changing it refetches without rebuilding the page state.
+final importsStatusFilterProvider = StateProvider<String?>((ref) => null);
+
+final importsListProvider = FutureProvider.autoDispose<List<ImportPreview>>((ref) async {
+  final status = ref.watch(importsStatusFilterProvider);
+  return ref.watch(importsApiProvider).list(status: status);
+});
+
+/// A single import's preview. For an uncommitted import the server recomputes counts and
+/// reconciliation on every read, so this is deliberately re-fetched rather than cached from
+/// the list response.
+final importPreviewProvider =
+    FutureProvider.autoDispose.family<ImportPreview, int>((ref, id) async {
+  return ref.watch(importsApiProvider).get(id);
+});
+
+/// Everything whose numbers change once events land in (or move inside) the ledger:
+/// portfolio, holdings, allocation, the value series, the dashboard and the event list.
+/// Called after a successful commit and after every pending-instrument resolve.
+void invalidateLedgerDependents(WidgetRef ref) {
+  invalidatePortfolioProviders(ref);
+  invalidateHomeProviders(ref);
+  ref.invalidate(eventsControllerProvider);
+}