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/en.json

@@ -1218,6 +1218,7 @@
       "cannotDeleteHasSubscriptions": "Cannot delete: has active subscriptions",
       "confirmDelete": "Delete tariff?",
       "confirmDeleteText": "This action cannot be undone. The tariff will be permanently deleted.",
+      "deleteSuccess": "Tariff deleted successfully",
       "days": "days",
       "days_one": "{{count}} day",
       "days_other": "{{count}} days",