Refactor notification handling and streamline router registration

- Replaced legacy notification functions with a unified NotificationService for better maintainability and clarity.
- Updated the main bot router registration to utilize a root router, simplifying the inclusion of user and admin routes.
- Removed unused middleware and helper functions to enhance code cleanliness and focus on essential components.
- Improved localization by adding new error messages for user interactions.

bot/services/notification_service.py

@@ -295,51 +295,4 @@ class NotificationService:
         if to_admins:
             await self._send_to_admins(message)
 
-
-# Legacy functions for backward compatibility
-async def notify_admins(bot: Bot, settings: Settings, i18n: JsonI18n,
-                        message_key: str, parse_mode: str | None = None,
-                        **kwargs) -> None:
-    if not settings.ADMIN_IDS:
-        return
-    admin_lang = settings.DEFAULT_LANGUAGE
-    msg = i18n.gettext(admin_lang, message_key, **kwargs)
-    for admin_id in settings.ADMIN_IDS:
-        try:
-            await bot.send_message(admin_id, msg, parse_mode=parse_mode)
-        except Exception as e:
-            logging.error(f"Failed to send admin notification to {admin_id}: {e}")
-
-
-async def notify_admin_new_trial(bot: Bot, settings: Settings, i18n: JsonI18n,
-                                 user_id: int, end_date: datetime) -> None:
-    """Send notification to admins about new trial activation (legacy)"""
-    notification_service = NotificationService(bot, settings, i18n)
-    await notification_service.notify_trial_activation(user_id, end_date)
-
-
-
-
-
-async def notify_admin_promo_activation(bot: Bot, settings: Settings,
-                                        i18n: JsonI18n, user_id: int,
-                                        code: str,
-                                        bonus_days: int) -> None:
-    await notify_admins(
-        bot,
-        settings,
-        i18n,
-        "admin_promo_activation_notification",
-        user_id=user_id,
-        code=code,
-        bonus_days=bonus_days,
-    )
-
-
-async def notify_admin_panel_sync(bot: Bot, settings: Settings,
-                                  i18n: JsonI18n, status: str,
-                                  details: str, users_processed: int,
-                                  subs_synced: int) -> None:
-    """Send notification to admins about panel sync (legacy)"""
-    notification_service = NotificationService(bot, settings, i18n)
-    await notification_service.notify_panel_sync(status, details, users_processed, subs_synced)
+# Removed legacy helper functions that duplicated NotificationService API