feat(cabinet): legal footer on login + admin toggle

Adds a legal footer (Public Offer / Privacy / Recurring Payments) under the
login card, gated by CABINET_FOOTER_ENABLED (backend endpoint added in bot
PR #3011), plus an admin toggle in BrandingTab and ru/en/fa/zh i18n.

Footer-only subset of PR #464 — excludes the unrelated storePartnerClickId
helper and the version/CHANGELOG churn.

Co-authored-by: smediainfo <dev@matrixvpn.top>

src/locales/en.json

@@ -2228,7 +2228,9 @@
         "telegramOidcClientSecret": "Client Secret"
       },
       "offlineConv": "Offline Conversions",
-      "apiKey": "API Key"
+      "apiKey": "API Key",
+      "legalFooter": "Legal Footer",
+      "legalFooterDesc": "Links to the offer, privacy policy and recurring payments at the bottom of the login page"
     },
     "bulkActions": {
       "title": "Bulk Actions",
@@ -5265,5 +5267,10 @@
     "empty": "You have no subscriptions yet",
     "emptyDesc": "Choose a tariff to get started",
     "title": "My subscriptions"
+  },
+  "footer": {
+    "offer": "Public Offer",
+    "privacy": "Privacy Policy",
+    "recurrent": "Recurring Payments"
   }
 }

src/locales/fa.json

@@ -1908,7 +1908,9 @@
         "telegramOidcClientSecret": "Client Secret"
       },
       "offlineConv": "تبدیل‌های آفلاین",
-      "apiKey": "کلید API"
+      "apiKey": "کلید API",
+      "legalFooter": "پاورقی حقوقی",
+      "legalFooterDesc": "پیوند به پیشنهاد، سیاست حریم خصوصی و پرداخت‌های مکرر در پایین صفحه ورود"
     },
     "buttons": {
       "color": "رنگ دکمه",
@@ -4899,5 +4901,10 @@
     "empty": "هنوز اشتراکی ندارید",
     "emptyDesc": "برای شروع تعرفه‌ای انتخاب کنید",
     "title": "اشتراک‌های من"
+  },
+  "footer": {
+    "offer": "پیشنهاد عمومی",
+    "privacy": "سیاست حفظ حریم خصوصی",
+    "recurrent": "پرداخت‌های مکرر"
   }
 }

src/locales/ru.json

@@ -2742,7 +2742,9 @@
         "MODERATION": "Модерация"
       },
       "offlineConv": "Офлайн-конверсии",
-      "apiKey": "API-ключ"
+      "apiKey": "API-ключ",
+      "legalFooter": "Юридический футер",
+      "legalFooterDesc": "Ссылки на оферту, политику и рекуррентные платежи внизу страницы входа"
     },
     "buttons": {
       "color": "Цвет кнопки",
@@ -5827,5 +5829,10 @@
     "empty": "У вас пока нет подписок",
     "emptyDesc": "Выберите тариф, чтобы начать пользоваться сервисом",
     "title": "Мои подписки"
+  },
+  "footer": {
+    "offer": "Публичная оферта",
+    "privacy": "Политика конфиденциальности",
+    "recurrent": "Рекуррентные платежи"
   }
 }

src/locales/zh.json

@@ -1973,7 +1973,9 @@
         "telegramOidcClientSecret": "Client Secret"
       },
       "offlineConv": "离线转化",
-      "apiKey": "API 密钥"
+      "apiKey": "API 密钥",
+      "legalFooter": "法律页脚",
+      "legalFooterDesc": "登录页面底部的要约、隐私政策和定期付款链接"
     },
     "buttons": {
       "color": "按钮颜色",
@@ -4898,5 +4900,10 @@
     "empty": "您还没有订阅",
     "emptyDesc": "选择套餐以开始使用",
     "title": "我的订阅"
+  },
+  "footer": {
+    "offer": "公开要约",
+    "privacy": "隐私政策",
+    "recurrent": "定期付款"
   }
 }