feat: bulk delete subscription + fix sub-rows showing for filtered single subs

- Add "Удалить подписки" action with red trash icon, destructive
  warning dialog (red border, irreversible action notice)
- Fix canExpand: show sub-rows when isMultiTariff && subs > 0
  (was > 1, hiding single filtered subscription results)
- i18n: deleteSubscription action + warning/hint (ru + en)

src/api/adminBulkActions.ts

@@ -11,7 +11,8 @@ export type BulkActionType =
   | 'add_balance'
   | 'assign_promo_group'
   | 'grant_subscription'
-  | 'set_devices';
+  | 'set_devices'
+  | 'delete_subscription';
 
 export interface BulkActionRequest {
   action: BulkActionType;