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/locales/en.json

@@ -120,6 +120,27 @@
       "receivedMessage": "Payment of {{amount}} {{currency}} received"
     }
   },
+  "successNotification": {
+    "balanceTopup": {
+      "title": "Balance topped up!"
+    },
+    "subscriptionActivated": {
+      "title": "Subscription activated!"
+    },
+    "subscriptionRenewed": {
+      "title": "Subscription renewed!"
+    },
+    "subscriptionPurchased": {
+      "title": "Subscription purchased!"
+    },
+    "amount": "Amount",
+    "price": "Price",
+    "newBalance": "New balance",
+    "tariff": "Tariff",
+    "validUntil": "Valid until",
+    "goToSubscription": "Go to Subscription",
+    "goToBalance": "Go to Balance"
+  },
   "auth": {
     "login": "Login",
     "register": "Register",

src/locales/fa.json

@@ -114,6 +114,27 @@
       "receivedMessage": "پرداخت {{amount}} {{currency}} دریافت شد"
     }
   },
+  "successNotification": {
+    "balanceTopup": {
+      "title": "موجودی شارژ شد!"
+    },
+    "subscriptionActivated": {
+      "title": "اشتراک فعال شد!"
+    },
+    "subscriptionRenewed": {
+      "title": "اشتراک تمدید شد!"
+    },
+    "subscriptionPurchased": {
+      "title": "اشتراک خریداری شد!"
+    },
+    "amount": "مبلغ",
+    "price": "قیمت",
+    "newBalance": "موجودی جدید",
+    "tariff": "تعرفه",
+    "validUntil": "معتبر تا",
+    "goToSubscription": "رفتن به اشتراک",
+    "goToBalance": "رفتن به موجودی"
+  },
   "auth": {
     "login": "ورود",
     "register": "ثبت نام",

src/locales/ru.json

@@ -123,6 +123,27 @@
       "receivedMessage": "Получен платёж на сумму {{amount}} {{currency}}"
     }
   },
+  "successNotification": {
+    "balanceTopup": {
+      "title": "Баланс пополнен!"
+    },
+    "subscriptionActivated": {
+      "title": "Подписка активирована!"
+    },
+    "subscriptionRenewed": {
+      "title": "Подписка продлена!"
+    },
+    "subscriptionPurchased": {
+      "title": "Подписка оплачена!"
+    },
+    "amount": "Сумма",
+    "price": "Стоимость",
+    "newBalance": "Новый баланс",
+    "tariff": "Тариф",
+    "validUntil": "Действует до",
+    "goToSubscription": "Перейти к подписке",
+    "goToBalance": "Перейти к балансу"
+  },
   "auth": {
     "login": "Вход",
     "register": "Регистрация",

src/locales/zh.json

@@ -114,6 +114,27 @@
       "receivedMessage": "收到付款 {{amount}} {{currency}}"
     }
   },
+  "successNotification": {
+    "balanceTopup": {
+      "title": "余额已充值！"
+    },
+    "subscriptionActivated": {
+      "title": "订阅已激活！"
+    },
+    "subscriptionRenewed": {
+      "title": "订阅已续期！"
+    },
+    "subscriptionPurchased": {
+      "title": "订阅已购买！"
+    },
+    "amount": "金额",
+    "price": "价格",
+    "newBalance": "新余额",
+    "tariff": "套餐",
+    "validUntil": "有效期至",
+    "goToSubscription": "查看订阅",
+    "goToBalance": "查看余额"
+  },
   "auth": {
     "login": "登录",
     "register": "注册",