feat(payment, chat): promo code mocked BottomSheet added

lib/features/payment/presentation/payment_flow.dart

@@ -0,0 +1,49 @@
+import 'package:eatvio_app/features/payment/presentation/widgets/promo_code_gate_bottom_sheet.dart';
+import 'package:eatvio_app/features/payment/presentation/widgets/promo_code_modal.dart';
+import 'package:eatvio_app/features/payment/presentation/widgets/sbp_banks_bottom_sheet.dart';
+import 'package:eatvio_app/generated/l10n.dart';
+import 'package:flutter/material.dart';
+
+/// Оркестрирует флоу оплаты консультации:
+/// гейт «У вас есть промокод?» → (Да → форма промокода) → SbpBanks.
+Future<void> showConsultationPaymentFlow(
+  BuildContext context, {
+  required int planId,
+  Future<bool?> Function(BuildContext)? showGate,
+  Future<PromoCodeResult?> Function(BuildContext, {Future<PromoValidation> Function(String)? onValidate})? showForm,
+  Future<void> Function(BuildContext, {required int planId})? showSbp,
+}) async {
+  final gate = showGate ?? _showGate;
+  final form = showForm ?? _showForm;
+  final sbp = showSbp ?? _showSbp;
+  final s = S.of(context);
+
+  final gateChoice = await gate(context);
+  if (gateChoice == null || !context.mounted) return;
+
+  if (gateChoice) {
+    final formResult = await form(
+      context,
+      onValidate: (_) async => PromoValidation.failure(s.promo_invalid),
+    );
+    if (formResult == null || !context.mounted) return;
+  }
+
+  if (!context.mounted) return;
+  await sbp(context, planId: planId);
+}
+
+Future<bool?> _showGate(BuildContext context) {
+  return showPromoCodeGateBottomSheet(context);
+}
+
+Future<PromoCodeResult?> _showForm(
+  BuildContext context, {
+  Future<PromoValidation> Function(String)? onValidate,
+}) {
+  return ItvioPromoCodeModal.show(context, onValidate: onValidate);
+}
+
+Future<void> _showSbp(BuildContext context, {required int planId}) {
+  return showSbpBanksBottomSheet(context, planId: planId);
+}