feat: add useNotify hook for unified notifications

- Created useNotify hook (src/platform/hooks/useNotify.ts):
  - In Telegram Mini App: uses native showPopup
  - In browser: uses beautiful Toast component
  - Methods: notify(), success(), error(), warning(), info()

- AdminTariffs: improved deletion UX
  - Uses useNotify.warning when tariff has subscriptions
  - Uses useDestructiveConfirm for delete confirmation
  - Shows success toast after deletion
  - Removed custom modal dialog

- AdminEmailTemplates: unified notification style
  - Replaced dialog.alert with useNotify.warning
  - Now shows beautiful Toast on mobile browser

- Added deleteSuccess i18n translations (ru, en, zh, fa)

src/locales/ru.json

@@ -1728,6 +1728,7 @@
       "cannotDeleteHasSubscriptions": "Нельзя удалить: есть активные подписки",
       "confirmDelete": "Удалить тариф?",
       "confirmDeleteText": "Это действие нельзя отменить. Тариф будет удален навсегда.",
+      "deleteSuccess": "Тариф успешно удален",
       "days": "дней",
       "days_one": "{{count}} день",
       "days_few": "{{count}} дня",