feat: публичные лендинг-страницы для быстрой покупки VPN-подписок

- QuickPurchase: публичная страница покупки с выбором тарифа/периода/оплаты
- PurchaseSuccess: статус покупки с поллингом и копированием ссылки
- AdminLandings: управление лендингами (создание, сортировка, удаление)
- AdminLandingEditor: полнофункциональный редактор лендинга
- API-клиент landings.ts для всех эндпоинтов
- Роутинг /buy/:slug и /buy/success/:token
- Локализация ru/en/zh/fa для всех текстов лендинга
- Санитизация HTML/CSS, rate limit защита, DOMPurify

src/locales/en.json

@@ -235,13 +235,13 @@
     "connectDevice": "Connect Device",
     "devicesConnected": "{{count}} connected",
     "devicesOfMax": "{{used}} of {{max}} connected",
+    "devicesConnectedUnlimited": "{{used}} connected · unlimited",
     "devicesShort": "dev.",
     "trafficUsage": "{{used}} / {{limit}} GB",
     "trafficUsageTitle": "Traffic Usage",
     "usedTraffic": "used {{amount}}",
     "usedSuffix": "used",
     "unlimited": "Unlimited",
-    "unlimitedTraffic": "Unlimited traffic",
     "tariff": "Tariff",
     "validUntil": "until {{date}}",
     "remaining": "Remaining",
@@ -1043,7 +1043,8 @@
       "roleAssign": "Role Assignment",
       "policies": "Access Policies",
       "auditLog": "Audit Log",
-      "salesStats": "Sales Statistics"
+      "salesStats": "Sales Statistics",
+      "landings": "Landings"
     },
     "panel": {
       "title": "Admin Panel",
@@ -1076,7 +1077,8 @@
       "roleAssignDesc": "Assign and revoke user roles",
       "policiesDesc": "Configure ABAC access policies",
       "auditLogDesc": "Review system activity and access history",
-      "salesStatsDesc": "Sales analytics and trends"
+      "salesStatsDesc": "Sales analytics and trends",
+      "landingsDesc": "Quick purchase landing pages"
     },
     "salesStats": {
       "title": "Sales Statistics",
@@ -3138,6 +3140,51 @@
         "loadFailed": "Failed to load audit log",
         "retry": "Try again"
       }
+    },
+    "landings": {
+      "title": "Landing Pages",
+      "create": "Create Landing",
+      "edit": "Edit",
+      "slug": "URL Identifier",
+      "slugHint": "Lowercase, numbers and hyphens",
+      "pageTitle": "Title",
+      "subtitle": "Subtitle",
+      "footerText": "Footer (HTML)",
+      "features": "Features",
+      "addFeature": "Add",
+      "featureIcon": "Icon",
+      "featureTitle": "Title",
+      "featureDesc": "Description",
+      "tariffs": "Plans",
+      "selectTariffs": "Select plans",
+      "periods": "Periods",
+      "paymentMethods": "Payment Methods",
+      "addMethod": "Add method",
+      "methodId": "Method ID",
+      "methodName": "Name",
+      "methodDesc": "Description",
+      "methodIcon": "Icon URL",
+      "gifts": "Gifts",
+      "giftEnabled": "Gift purchases",
+      "customCss": "CSS",
+      "seo": "SEO",
+      "metaTitle": "Meta Title",
+      "metaDesc": "Meta Description",
+      "active": "Active",
+      "inactive": "Inactive",
+      "purchases": "purchases",
+      "copyUrl": "Copy URL",
+      "urlCopied": "URL copied",
+      "deleteConfirm": "Delete landing \"{{title}}\"?",
+      "created": "Landing created",
+      "updated": "Landing updated",
+      "deleted": "Landing deleted",
+      "saveOrder": "Save order",
+      "orderSaved": "Order saved",
+      "general": "General",
+      "content": "Content",
+      "save": "Save",
+      "back": "Back"
     }
   },
   "adminUpdates": {
@@ -3865,5 +3912,44 @@
     "error": "Failed to merge accounts. Please try again later.",
     "expiresIn": "Expires in {{minutes}}",
     "merging": "Merging..."
+  },
+  "landing": {
+    "notFound": "Page not found",
+    "forMe": "For me",
+    "asGift": "As a gift",
+    "contactLabel": "Your email or @username",
+    "yourContact": "Your email or @username",
+    "contactPlaceholder": "email@example.com or @username",
+    "contactHint": "Enter email or Telegram @username",
+    "recipientLabel": "Gift recipient",
+    "recipientPlaceholder": "Recipient email or @username",
+    "giftMessageLabel": "Greeting (optional)",
+    "giftMessagePlaceholder": "Write a greeting...",
+    "chooseTariff": "Choose a plan",
+    "devices": "devices",
+    "paymentMethod": "Payment method",
+    "processing": "Processing...",
+    "payButton": "Pay {{price}}",
+    "accessFor": "Access for {{period}}",
+    "purchaseError": "Failed to create payment",
+    "purchaseNotFound": "Purchase not found",
+    "awaitingPayment": "Awaiting payment",
+    "awaitingPaymentDesc": "Complete the payment in the opened window",
+    "purchaseSuccess": "Payment successful!",
+    "keySentTo": "Subscription key sent to {{contact}}",
+    "giftSentTo": "Gift sent to {{contact}}",
+    "purchaseFailed": "Payment failed",
+    "purchaseFailedDesc": "Payment was unsuccessful. Try again.",
+    "subscriptionLink": "Subscription link",
+    "daysAccess": "days of access",
+    "error": "Error",
+    "gb": "GB",
+    "selectedTariff": "Tariff",
+    "period": "Period",
+    "total": "Total",
+    "pay": "Pay",
+    "choosePeriod": "Choose period",
+    "copied": "Copied!",
+    "copyLink": "Copy link"
   }
 }