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/index.ts

@@ -1,6 +1,8 @@
 export { AddonsTab } from './AddonsTab';
 export { DepositsTab } from './DepositsTab';
 export { DonutChart } from './DonutChart';
+export { DualAreaChart } from './DualAreaChart';
+export { MultiSeriesAreaChart } from './MultiSeriesAreaChart';
 export { PeriodSelector } from './PeriodSelector';
 export { RenewalsTab } from './RenewalsTab';
 export { SalesTab } from './SalesTab';