changed color theme to be black and added the ability to enter the amount in the recipient’s currency

frontend/pshared/lib/utils/payment/quotation_currency_resolver.dart

@@ -0,0 +1,57 @@
+import 'package:pshared/models/payment/methods/card.dart';
+import 'package:pshared/models/payment/methods/crypto_address.dart';
+import 'package:pshared/models/payment/methods/data.dart';
+import 'package:pshared/models/payment/methods/iban.dart';
+import 'package:pshared/models/payment/methods/russian_bank.dart';
+import 'package:pshared/models/payment/quote/quote.dart';
+
+
+class PaymentQuotationCurrencyResolver {
+  static String? resolveQuoteCurrency({
+    PaymentQuote? quote,
+    PaymentMethodData? paymentData,
+  }) {
+    final quoteCurrency = _normalizeCurrency(
+      quote?.amounts?.destinationSettlement?.currency,
+    );
+    if (quoteCurrency != null) return quoteCurrency;
+
+    if (paymentData == null) return null;
+
+    final metadataCurrency = _normalizeCurrency(
+      paymentData.metadata?['currency'],
+    );
+    if (metadataCurrency != null) return metadataCurrency;
+
+    if (paymentData is CryptoAddressPaymentMethod) {
+      return _normalizeCurrency(paymentData.asset?.tokenSymbol);
+    }
+
+    if (paymentData is RussianBankAccountPaymentMethod ||
+        paymentData is CardPaymentMethod) {
+      return 'RUB';
+    }
+
+    if (paymentData is IbanPaymentMethod) {
+      return 'EUR';
+    }
+
+    return null;
+  }
+
+  static bool isFxEnabled({
+    required String? sourceCurrency,
+    required String? quoteCurrency,
+  }) {
+    final normalizedSource = _normalizeCurrency(sourceCurrency);
+    final normalizedQuote = _normalizeCurrency(quoteCurrency);
+    if (normalizedSource == null || normalizedQuote == null) return false;
+    return normalizedSource != normalizedQuote;
+  }
+
+  static String? _normalizeCurrency(String? value) {
+    final normalized = value?.trim().toUpperCase();
+    if (normalized == null || normalized.isEmpty) return null;
+    return normalized;
+  }
+}