Fix activation date reference and update localization for promo code toggle success message

- Changed the reference from `created_at` to `activated_at` in the promo activations handler to accurately reflect the activation date.
- Updated the localization files for both English and Russian to remove HTML tags from the promo code toggle success message, enhancing clarity.

locales/en.json

@@ -420,7 +420,7 @@
   "admin_promo_toggle_status_button": "🔄 On/Off",
   "admin_promo_view_activations_button": "📋 Activations",
   "admin_promo_back_to_list_button": "⬅️ Back to list",
-  "admin_promo_toggle_success": "✅ Promo code <b>{code}</b> {status}",
+  "admin_promo_toggle_success": "✅ Promo code {code} {status}",
   "admin_promo_toggle_failed": "❌ Error changing promo code status",
   "admin_promo_no_activations": "📋 <b>Activations of promo code: {code}</b>\n\n❌ No activations found",
   "admin_promo_activations_header": "📋 <b>Activations of promo code: {code}</b>\n\n",

locales/ru.json

@@ -419,7 +419,7 @@
   "admin_promo_toggle_status_button": "🔄 Вкл/Выкл",
   "admin_promo_view_activations_button": "📋 Активации",
   "admin_promo_back_to_list_button": "⬅️ К списку",
-  "admin_promo_toggle_success": "✅ Промокод <b>{code}</b> {status}",
+  "admin_promo_toggle_success": "✅ Промокод {code} {status}",
   "admin_promo_toggle_failed": "❌ Ошибка изменения статуса промокода",
   "admin_promo_no_activations": "📋 <b>Активации промокода: {code}</b>\n\n❌ Активаций не найдено",
   "admin_promo_activations_header": "📋 <b>Активации промокода: {code}</b>\n\n",