refactor: delete dead Cake Pay/buy/exchange code; split di setup()

- Cake Pay: 36 files (~5.3k LOC) plus DI registrations, routes, and UI
  branches (feature was hard-disabled and unreachable)
- unreachable buy providers: robinhood, dfx, onramper, meld, kryptonim
  (~1.7k LOC); MoonPay untouched
- exchange providers that only existed as commented-out wiring:
  changenow, sideshift, chainflip, exolix, swaptrade, letsexchange,
  stealthex, xoswap, swapsxyz, thorchain, simpleswap (~5.2k LOC);
  Trocador untouched; ExchangeProviderDescription values and Hive
  adapters kept so stored trades and orders still deserialize
- di.dart setup() split from one 1,452-line function into 10 sequential
  chunk functions; registration execution order verified identical
  before and after (251 register calls)

lib/src/screens/dashboard/dashboard_page.dart

@@ -14,7 +14,6 @@ import 'package:hash_wallet/src/widgets/vulnerable_seeds_popup.dart';
 import 'package:hash_wallet/utils/device_info.dart';
 import 'package:hash_wallet/utils/feature_flag.dart';
 import 'package:hash_wallet/utils/version_comparator.dart';
-import 'package:hash_wallet/view_model/dashboard/cake_features_view_model.dart';
 import 'package:hash_wallet/generated/i18n.dart';
 import 'package:hash_wallet/routes.dart';
 import 'package:hash_wallet/src/screens/yat_emoji_id.dart';
@@ -327,7 +326,6 @@ class _DashboardPageView extends BasePage {
           label: S.of(context).apps,
           child: CakeFeaturesPage(
             dashboardViewModel: dashboardViewModel,
-            cakeFeaturesViewModel: getIt.get<CakeFeaturesViewModel>(),
           ),
         ),
       );

lib/src/screens/dashboard/desktop_widgets/desktop_dashboard_actions.dart

@@ -1,9 +1,7 @@
-import 'package:hash_wallet/di.dart';
 import 'package:hash_wallet/entities/main_actions.dart';
 import 'package:hash_wallet/src/screens/dashboard/desktop_widgets/desktop_action_button.dart';
 import 'package:hash_wallet/src/screens/dashboard/pages/cake_features_page.dart';
 import 'package:hash_wallet/view_model/dashboard/dashboard_view_model.dart';
-import 'package:hash_wallet/view_model/dashboard/cake_features_view_model.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_mobx/flutter_mobx.dart';
 
@@ -75,7 +73,6 @@ class DesktopDashboardActions extends StatelessWidget {
             Expanded(
               child: CakeFeaturesPage(
                 dashboardViewModel: dashboardViewModel,
-                cakeFeaturesViewModel: getIt.get<CakeFeaturesViewModel>(),
               ),
             ),
             ],

lib/src/screens/dashboard/pages/balance/crypto_balance_widget.dart

@@ -7,10 +7,8 @@ import 'package:hash_wallet/src/screens/dashboard/widgets/info_card.dart';
 import 'package:hash_wallet/src/widgets/alert_with_one_action.dart';
 import 'package:hash_wallet/src/widgets/alert_with_two_actions.dart';
 import 'package:hash_wallet/src/widgets/dashboard_card_widget.dart';
-import 'package:hash_wallet/src/widgets/introducing_card.dart';
 import 'package:hash_wallet/src/widgets/standard_switch.dart';
 import 'package:hash_wallet/themes/core/theme_extension.dart';
-import 'package:hash_wallet/utils/feature_flag.dart';
 import 'package:hash_wallet/utils/show_pop_up.dart';
 import 'package:hash_wallet/view_model/dashboard/dashboard_view_model.dart';
 import 'package:cw_core/wallet_info.dart';
@@ -139,18 +137,6 @@ class CryptoBalanceWidget extends StatelessWidget {
                         ),
                       ],
                     )),
-          Observer(
-            builder: (_) {
-              if (dashboardViewModel.balanceViewModel.isShowCard && FeatureFlag.isCakePayEnabled) {
-                return IntroducingCard(
-                    title: S.of(context).introducing_cake_pay,
-                    subTitle: S.of(context).cake_pay_learn_more,
-                    borderColor: Theme.of(context).colorScheme.outline,
-                    closeCard: dashboardViewModel.balanceViewModel.disableIntroCakePayCard);
-              }
-              return Container();
-            },
-          ),
           Observer(builder: (_) {
             if (!dashboardViewModel.showRepWarning) {
               return const SizedBox();

lib/src/screens/dashboard/pages/cake_features_page.dart

@@ -1,24 +1,17 @@
-import 'dart:io';
-
 import 'package:hash_wallet/generated/i18n.dart';
 import 'package:hash_wallet/new-ui/widgets/apps_widget.dart';
-import 'package:hash_wallet/routes.dart';
 import 'package:hash_wallet/src/widgets/hash_image_widget.dart';
 import 'package:hash_wallet/src/widgets/dashboard_card_widget.dart';
 import 'package:hash_wallet/utils/feature_flag.dart';
-import 'package:hash_wallet/view_model/dashboard/cake_features_view_model.dart';
 import 'package:hash_wallet/view_model/dashboard/dashboard_view_model.dart';
-import 'package:cw_core/utils/print_verbose.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_mobx/flutter_mobx.dart';
-import 'package:url_launcher/url_launcher.dart';
 import 'package:hash_wallet/src/widgets/gradient_background.dart';
 
 class CakeFeaturesPage extends StatelessWidget {
-  CakeFeaturesPage({required this.dashboardViewModel, required this.cakeFeaturesViewModel});
+  CakeFeaturesPage({required this.dashboardViewModel});
 
   final DashboardViewModel dashboardViewModel;
-  final CakeFeaturesViewModel cakeFeaturesViewModel;
 
   @override
   Widget build(BuildContext context) {
@@ -102,23 +95,4 @@ class CakeFeaturesPage extends StatelessWidget {
     );
   }
 
-  void _onCakePayTap(BuildContext context) {
-    if (Platform.isMacOS) {
-      _launchUrl("buy.cakepay.com");
-    } else {
-      _navigatorToGiftCardsPage(context);
-    }
-  }
-
-  void _launchUrl(String url) {
-    try {
-      launchUrl(Uri.https(url), mode: LaunchMode.externalApplication);
-    } catch (e) {
-      printV(e);
-    }
-  }
-
-  void _navigatorToGiftCardsPage(BuildContext context) {
-    Navigator.pushNamed(context, Routes.cakePayCardsPage);
-  }
 }

lib/src/screens/exchange/exchange_page.dart

@@ -1,6 +1,4 @@
 import 'package:hash_wallet/exchange/exchange_provider_description.dart';
-import 'package:hash_wallet/exchange/provider/chainflip_exchange_provider.dart';
-import 'package:hash_wallet/exchange/provider/thorchain_exchange.provider.dart';
 import 'package:hash_wallet/core/auth_service.dart';
 import 'package:hash_wallet/di.dart';
 import 'package:hash_wallet/src/screens/exchange/widgets/desktop_exchange_cards_section.dart';
@@ -542,14 +540,7 @@ class ExchangePage extends BasePage {
       if (depositAmountController.text != exchangeViewModel.depositAmount &&
           depositAmountController.text != S.of(context).all) {
         exchangeViewModel.isSendAllEnabled = false;
-        final isThorChain = exchangeViewModel.selectedProviders
-            .any((provider) => provider is ThorChainExchangeProvider);
-        final isChainflip = exchangeViewModel.selectedProviders
-            .any((provider) => provider is ChainflipExchangeProvider);
-
-        _depositAmountDebounce = isThorChain || isChainflip
-            ? Debounce(Duration(milliseconds: 1000))
-            : Debounce(Duration(milliseconds: 500));
+        _depositAmountDebounce = Debounce(Duration(milliseconds: 500));
 
         _depositAmountDebounce.run(() {
           exchangeViewModel.calculateBestRate();

lib/src/screens/order_details/cake_pay_detail_list_card_item.dart

@@ -1,27 +0,0 @@
-import 'package:hash_wallet/cake_pay/src/models/cake_pay_order.dart';
-import 'package:hash_wallet/src/screens/transaction_details/standart_list_item.dart';
-import 'package:flutter/material.dart';
-
-class CakePayDetailsListCardItem extends StandartListItem {
-  CakePayDetailsListCardItem({
-    required String title,
-    required String value,
-    required this.id,
-    required this.createdAt,
-    this.price,
-    this.quantity,
-    required this.from,
-    required this.to,
-    required this.onTap,
-    required this.cards,
-  }) : super(title: title, value: value);
-
-  final String id;
-  final String createdAt;
-  final String? price;
-  final String? quantity;
-  final String from;
-  final String to;
-  final void Function(BuildContext) onTap;
-  final List<OrderCard> cards;
-}

lib/src/screens/order_details/order_details_page.dart

@@ -1,6 +1,4 @@
-import 'package:hash_wallet/src/screens/order_details/cake_pay_detail_list_card_item.dart';
 import 'package:hash_wallet/src/screens/trade_details/trade_details_status_item.dart';
-import 'package:hash_wallet/src/widgets/cake_pay_order_list_card.dart';
 import 'package:hash_wallet/src/widgets/standard_list.dart';
 import 'package:hash_wallet/src/widgets/standard_list_status_row.dart';
 import 'package:hash_wallet/themes/core/material_base_theme.dart';
@@ -64,21 +62,6 @@ class OrderDetailsPageBodyState extends State<OrderDetailsPageBody> {
               return StandardListStatusRow(title: item.title, value: item.value);
             }
 
-            if (item is CakePayDetailsListCardItem) {
-              final cardImagePath = (item.cards.isNotEmpty) ? item.cards.first.cardImagePath : null;
-
-              return CakePayOrderListCard(
-                id: item.id,
-                create: item.createdAt,
-                price: item.price,
-                quantity: item.quantity,
-                pair: '${item.from} → ${item.to}',
-                currentTheme: widget.currentTheme.type,
-                onTap: item.onTap,
-                backgroundImage: cardImagePath,
-              );
-            }
-
             if (item is TrackTradeListItem) {
               return GestureDetector(
                   onTap: item.onTap,