fix(format): convert price by exchange rate on landings and gift page

formatPrice from utils/format.ts only swapped the currency symbol
(220 ₽ -> ¥220) without converting the underlying amount, because it
had no source of exchange rates and the landing/gift pages never called
the useCurrency hook that knew how to fetch them.

- Add a module-level rates cache in utils/format with setExchangeRates
  setter. formatPrice now converts kopeks/100 from RUB to the target
  currency via currencyApi.convertFromRub when rates are cached.
- useCurrency pushes its loaded rates into that cache so any subsequent
  formatPrice call benefits, including subcomponents that cannot easily
  receive a prop.
- Call useCurrency in QuickPurchase, GiftSubscription, and
  AdminLandingEditor — the only entry points whose subcomponents still
  use the synchronous formatPrice (everything else already routes
  through useCurrency.formatAmount).

For RU locale behavior is unchanged. For EN/ZH/FA the amount is now
divided by the per-currency rate and formatted via Intl.NumberFormat
with 2 fraction digits (0 for IRR since amounts are large).

src/hooks/useCurrency.ts

@@ -1,7 +1,8 @@
-import { useCallback, useMemo } from 'react';
+import { useCallback, useEffect, useMemo } from 'react';
 import { useQuery } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
 import { currencyApi, type ExchangeRates } from '../api/currency';
+import { setExchangeRates as setGlobalExchangeRates } from '../utils/format';
 
 // Map language to currency
 const LANGUAGE_CURRENCY_MAP: Record<string, keyof ExchangeRates | 'RUB'> = {
@@ -30,6 +31,12 @@ export function useCurrency() {
     retry: 2,
   });
 
+  // Делимся курсом с синхронным formatPrice из utils/format.ts —
+  // у него нет своего источника rates, а на лендинге его дёргают subcomponents.
+  useEffect(() => {
+    setGlobalExchangeRates(exchangeRates);
+  }, [exchangeRates]);
+
   // Get current language and currency
   const currentLanguage = i18n.language;
   const targetCurrency = LANGUAGE_CURRENCY_MAP[currentLanguage] || 'USD';

src/pages/AdminLandingEditor.tsx

@@ -13,6 +13,7 @@ import {
 } from '../api/landings';
 import { tariffsApi, TariffListItem, PeriodPrice } from '../api/tariffs';
 import { formatPrice } from '../utils/format';
+import { useCurrency } from '../hooks/useCurrency';
 import { adminPaymentMethodsApi } from '../api/adminPaymentMethods';
 import { Toggle, LocaleTabs, LocalizedInput } from '../components/admin';
 import { BackgroundConfigEditor } from '../components/admin/BackgroundConfigEditor';
@@ -97,6 +98,9 @@ export default function AdminLandingEditor() {
   const { capabilities } = usePlatform();
   const isEdit = !!id;
 
+  // Прогреваем кэш курсов валют для formatPrice (preview лендинга в не-RU локали).
+  useCurrency();
+
   // Section visibility
   const [openSections, setOpenSections] = useState<Record<string, boolean>>({
     general: true,

src/pages/GiftSubscription.tsx

@@ -19,6 +19,7 @@ import { cn } from '../lib/utils';
 import { copyToClipboard } from '../utils/clipboard';
 import { getApiErrorMessage } from '../utils/api-error';
 import { formatPrice } from '../utils/format';
+import { useCurrency } from '../hooks/useCurrency';
 import { usePlatform, useHaptic } from '@/platform';
 
 function GiftIcon({ className }: { className?: string }) {
@@ -1286,6 +1287,9 @@ export default function GiftSubscription() {
   const { t } = useTranslation();
   const [searchParams] = useSearchParams();
 
+  // Прогреваем кэш курсов валют для formatPrice (см. QuickPurchase).
+  useCurrency();
+
   // URL params: ?tab=activate&code=TOKEN for auto-activation
   const urlTab = searchParams.get('tab') as TabId | null;
   const rawCode = searchParams.get('code');

src/pages/QuickPurchase.tsx

@@ -19,6 +19,7 @@ import LanguageSwitcher from '../components/LanguageSwitcher';
 import { cn } from '../lib/utils';
 import { getApiErrorMessage } from '../utils/api-error';
 import { formatPrice } from '../utils/format';
+import { useCurrency } from '../hooks/useCurrency';
 
 function detectContactType(value: string): 'email' | 'telegram' {
   return value.startsWith('@') ? 'telegram' : 'email';
@@ -795,6 +796,10 @@ export default function QuickPurchase() {
   const { t, i18n } = useTranslation();
   const queryClient = useQueryClient();
 
+  // Подгружаем курсы валют, чтобы formatPrice конвертировал суммы для не-RU локалей
+  // (хук кладёт rates в глобальный кэш utils/format.ts).
+  useCurrency();
+
   // Fetch config
   const {
     data: config,

src/utils/format.ts

@@ -10,27 +10,52 @@ export function formatUptime(seconds: number): string {
 }
 
 import i18next from 'i18next';
+import { currencyApi, type ExchangeRates } from '../api/currency';
 
-const LANG_CURRENCY_MAP: Record<string, { currency: string; locale: string; symbol: string }> = {
+const LANG_CURRENCY_MAP: Record<
+  string,
+  { currency: string; locale: string; symbol: string; key?: keyof ExchangeRates }
+> = {
   ru: { currency: 'RUB', locale: 'ru-RU', symbol: '₽' },
-  en: { currency: 'USD', locale: 'en-US', symbol: '$' },
-  zh: { currency: 'CNY', locale: 'zh-CN', symbol: '¥' },
-  fa: { currency: 'IRR', locale: 'fa-IR', symbol: '﷼' },
+  en: { currency: 'USD', locale: 'en-US', symbol: '$', key: 'USD' },
+  zh: { currency: 'CNY', locale: 'zh-CN', symbol: '¥', key: 'CNY' },
+  fa: { currency: 'IRR', locale: 'fa-IR', symbol: '﷼', key: 'IRR' },
 };
 
 const DEFAULT_CURRENCY = { currency: 'RUB', locale: 'ru-RU', symbol: '₽' };
 
+// Глобальный кэш курсов. Заполняется один раз из useCurrency (см. setExchangeRates ниже)
+// и используется здесь синхронно. Без него formatPrice падал в "просто замена символа",
+// что давало пользователю на лендинге `¥220` вместо реально конвертированной суммы.
+let cachedExchangeRates: ExchangeRates | null = null;
+
+export function setExchangeRates(rates: ExchangeRates | null): void {
+  cachedExchangeRates = rates;
+}
+
 export function formatPrice(kopeks: number, lang?: string): string {
   const resolvedLang = lang || i18next.language || 'ru';
   const config = LANG_CURRENCY_MAP[resolvedLang] || DEFAULT_CURRENCY;
-  const rubles = kopeks / 100;
+  let amount = kopeks / 100;
+
+  // Конвертация по курсу для не-рублёвых локалей. Без rates fallback на сырую сумму
+  // (поведение до фикса), чтобы первый рендер до загрузки курсов не отдавал NaN.
+  if (config.key && cachedExchangeRates) {
+    amount = currencyApi.convertFromRub(amount, config.key, cachedExchangeRates);
+  }
+
+  // Для IRR суммы большие — без дробной части.
+  const maximumFractionDigits = config.currency === 'IRR' ? 0 : 2;
+
   try {
     return new Intl.NumberFormat(config.locale, {
       style: 'currency',
       currency: config.currency,
-      maximumFractionDigits: 0,
-    }).format(rubles);
+      maximumFractionDigits,
+    }).format(amount);
   } catch {
-    return `${Math.round(rubles)} ${config.symbol}`;
+    const rounded =
+      maximumFractionDigits === 0 ? Math.round(amount) : Math.round(amount * 100) / 100;
+    return `${rounded} ${config.symbol}`;
   }
 }