feat: enhance sales stats with device stats, per-tariff charts, and dual-series trials

- Add DualAreaChart component for two-series visualization (registrations vs trials)
- Add MultiSeriesAreaChart component for N-series tariff breakdown with dynamic pivoting
- AddonsTab: add device purchases and device revenue stat cards
- SalesTab: add per-tariff daily sales chart using MultiSeriesAreaChart
- TrialsTab: replace single-series area chart with dual-series registrations + trials chart
- Update TypeScript interfaces to match backend schema changes
- Add i18n keys for all new UI elements across en, ru, zh, fa locales

src/components/sales-stats/SalesTab.tsx

@@ -1,3 +1,4 @@
+import { useMemo } from 'react';
 import { useQuery } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
 
@@ -8,6 +9,7 @@ import { useCurrency } from '../../hooks/useCurrency';
 import { StatCard } from '../stats';
 
 import { DonutChart } from './DonutChart';
+import { MultiSeriesAreaChart } from './MultiSeriesAreaChart';
 import { SimpleAreaChart } from './SimpleAreaChart';
 import { SimpleBarChart } from './SimpleBarChart';
 
@@ -25,6 +27,13 @@ export function SalesTab({ params }: SalesTabProps) {
     staleTime: SALES_STATS.STALE_TIME,
   });
 
+  const dailyByTariffData = useMemo(
+    () =>
+      data?.daily_by_tariff.map((i) => ({ date: i.date, key: i.tariff_name, value: i.count })) ??
+      [],
+    [data?.daily_by_tariff],
+  );
+
   if (isLoading) {
     return (
       <div className="animate-pulse space-y-4">
@@ -77,6 +86,13 @@ export function SalesTab({ params }: SalesTabProps) {
         chartId="sales-daily"
         valueLabel={t('admin.salesStats.summary.revenue')}
       />
+
+      <MultiSeriesAreaChart
+        data={dailyByTariffData}
+        title={t('admin.salesStats.sales.dailyByTariff')}
+        chartId="sales-daily-by-tariff"
+        valueLabel={t('admin.salesStats.sales.subscriptions')}
+      />
     </div>
   );
 }