feat: add success notification modal for balance and subscription events

- Add zustand store for global success notifications
- Create SuccessNotificationModal component with prominent UI
- Update WebSocketNotifications to show modal for important events:
  - balance.topup shows balance topped up modal
  - subscription.activated shows activation modal
  - subscription.renewed shows renewal modal
- Add translations for all locales (ru, en, zh, fa)

src/store/successNotification.ts

@@ -0,0 +1,39 @@
+import { create } from 'zustand';
+
+export type SuccessNotificationType =
+  | 'balance_topup'
+  | 'subscription_activated'
+  | 'subscription_renewed'
+  | 'subscription_purchased';
+
+export interface SuccessNotificationData {
+  type: SuccessNotificationType;
+  /** Amount in kopeks (for balance or subscription price) */
+  amountKopeks?: number;
+  /** New balance in kopeks */
+  newBalanceKopeks?: number;
+  /** Subscription expiry date ISO string */
+  expiresAt?: string;
+  /** Tariff name */
+  tariffName?: string;
+  /** Custom title override */
+  title?: string;
+  /** Custom message override */
+  message?: string;
+}
+
+interface SuccessNotificationState {
+  isOpen: boolean;
+  data: SuccessNotificationData | null;
+
+  show: (data: SuccessNotificationData) => void;
+  hide: () => void;
+}
+
+export const useSuccessNotification = create<SuccessNotificationState>((set) => ({
+  isOpen: false,
+  data: null,
+
+  show: (data) => set({ isOpen: true, data }),
+  hide: () => set({ isOpen: false, data: null }),
+}));