feat: add notifications module with bell UI, event listeners, and cleanup job

In-app notification system with topbar bell icon, dropdown panel,
mark-as-read/dismiss actions, and scheduled cleanup of old read
notifications. Includes event listeners for user.created and
user.deleted events, authorization policy, and full test coverage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/notifications/lib/Module/Notifications/Service/NotificationServicesFactory.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace MintyPHP\Module\Notifications\Service;
+
+class NotificationServicesFactory
+{
+    private ?NotificationService $notificationService = null;
+
+    public function __construct(
+        private readonly NotificationRepositoryFactory $notificationRepositoryFactory
+    ) {
+    }
+
+    public function createNotificationService(): NotificationService
+    {
+        return $this->notificationService ??= new NotificationService(
+            $this->notificationRepositoryFactory->createNotificationRepository()
+        );
+    }
+}