feat: add admin sales statistics dashboard with 5 analytics tabs

- Add sales stats API client with typed interfaces for all endpoints
- Implement AdminSalesStats page with summary cards and period selector
- Add TrialsTab with provider breakdown donut chart and daily area chart
- Add SalesTab with tariff/period breakdown and daily revenue chart
- Add RenewalsTab with period comparison and trend indicators
- Add AddonsTab with package breakdown bar chart
- Add DepositsTab with payment method breakdown bar chart
- Add SimpleBarChart, SimpleAreaChart, DonutChart components
- Add PeriodSelector with preset periods and custom date range
- Full responsive design (mobile/tablet/desktop/TG Mini App)
- ARIA accessibility (tablist, tab, tabpanel, aria-selected)
- Error handling with isError on all queries
- Empty data guards on all chart components
- i18n support across all 4 locales (en, ru, zh, fa)

src/components/sales-stats/AddonsTab.tsx

@@ -0,0 +1,81 @@
+import { useQuery } from '@tanstack/react-query';
+import { useTranslation } from 'react-i18next';
+
+import type { SalesStatsParams } from '../../api/adminSalesStats';
+import { salesStatsApi } from '../../api/adminSalesStats';
+import { SALES_STATS } from '../../constants/salesStats';
+import { useCurrency } from '../../hooks/useCurrency';
+import { StatCard } from '../stats';
+
+import { SimpleAreaChart } from './SimpleAreaChart';
+import { SimpleBarChart } from './SimpleBarChart';
+
+interface AddonsTabProps {
+  params: SalesStatsParams;
+}
+
+export function AddonsTab({ params }: AddonsTabProps) {
+  const { t } = useTranslation();
+  const { formatWithCurrency } = useCurrency();
+
+  const { data, isLoading, isError } = useQuery({
+    queryKey: ['sales-stats', 'addons', params],
+    queryFn: () => salesStatsApi.getAddons(params),
+    staleTime: SALES_STATS.STALE_TIME,
+  });
+
+  if (isLoading) {
+    return (
+      <div className="animate-pulse space-y-4">
+        {Array.from({ length: 3 }, (_, i) => (
+          <div key={i} className="h-24 rounded-xl bg-dark-800/30" />
+        ))}
+      </div>
+    );
+  }
+
+  if (isError || !data) {
+    return <div className="py-8 text-center text-red-400">{t('admin.salesStats.loadError')}</div>;
+  }
+
+  const packageBarData = data.by_package.map((item) => ({
+    name: `${item.traffic_gb} GB`,
+    value: item.count,
+  }));
+
+  const dailyData = data.daily.map((item) => ({
+    date: item.date,
+    value: item.count,
+  }));
+
+  return (
+    <div className="space-y-4">
+      <div className="grid grid-cols-1 gap-3 sm:grid-cols-3">
+        <StatCard
+          label={t('admin.salesStats.addons.totalPurchases')}
+          value={data.total_purchases}
+        />
+        <StatCard
+          label={t('admin.salesStats.addons.totalGb')}
+          value={`${data.total_gb_purchased} GB`}
+        />
+        <StatCard
+          label={t('admin.salesStats.addons.revenue')}
+          value={formatWithCurrency(data.addon_revenue_kopeks / SALES_STATS.KOPEKS_DIVISOR)}
+          valueClassName="text-success-400"
+        />
+      </div>
+
+      <div className="grid grid-cols-1 gap-4 lg:grid-cols-2">
+        <SimpleBarChart data={packageBarData} title={t('admin.salesStats.addons.byPackage')} />
+        <SimpleAreaChart
+          data={dailyData}
+          title={t('admin.salesStats.addons.dailyChart')}
+          chartId="addons-daily"
+          valueLabel={t('admin.salesStats.addons.purchases')}
+          color={SALES_STATS.BAR_COLORS[5]}
+        />
+      </div>
+    </div>
+  );
+}