feat: add reset traffic toggle on tariff switch

- Add reset_traffic parameter to previewTariffSwitch and switchTariff API calls
- Add reset_traffic_available/reset_traffic_default fields to TariffSwitchPreview type
- Add toggle switch in tariff switch preview modal (shown when backend enables it)
- Initialize toggle from server default (reset_traffic_default)
- Pass reset_traffic flag on switch execution
- Add translations for all 4 locales (ru, en, zh, fa)

src/locales/en.json

@@ -483,7 +483,9 @@
       "switched": "Tariff switched",
       "notEnoughBalance": "Insufficient balance",
       "dailyPayment": "Daily payment",
-      "dailyChargeDescription": "Charged daily from your balance"
+      "dailyChargeDescription": "Charged daily from your balance",
+      "resetTraffic": "Reset traffic",
+      "resetTrafficHint": "Reset used traffic when switching tariff"
     },
     "switchTraffic": {
       "title": "Change Traffic",

src/locales/fa.json

@@ -378,7 +378,9 @@
       "remainingDays": "روزهای باقی‌مانده",
       "switch": "تغییر",
       "title": "تغییر تعرفه",
-      "upgradeCost": "هزینه ارتقا"
+      "upgradeCost": "هزینه ارتقا",
+      "resetTraffic": "بازنشانی ترافیک",
+      "resetTrafficHint": "بازنشانی ترافیک مصرفی هنگام تغییر تعرفه"
     },
     "promoGroup": {
       "yourGroup": "گروه شما: {{name}}",

src/locales/ru.json

@@ -506,7 +506,9 @@
       "switched": "Тариф изменён",
       "notEnoughBalance": "Недостаточно средств",
       "dailyPayment": "Оплата за день",
-      "dailyChargeDescription": "Списывается ежедневно с баланса"
+      "dailyChargeDescription": "Списывается ежедневно с баланса",
+      "resetTraffic": "Сбросить трафик",
+      "resetTrafficHint": "Обнулить использованный трафик при смене тарифа"
     },
     "switchTraffic": {
       "title": "Изменить трафик",

src/locales/zh.json

@@ -378,7 +378,9 @@
       "remainingDays": "剩余天数",
       "switch": "切换",
       "title": "切换套餐",
-      "upgradeCost": "升级费用"
+      "upgradeCost": "升级费用",
+      "resetTraffic": "重置流量",
+      "resetTrafficHint": "切换套餐时重置已使用流量"
     },
     "promoGroup": {
       "yourGroup": "您的组：{{name}}",