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/pages/notifications/list-data().php

@@ -0,0 +1,34 @@
+<?php
+
+use MintyPHP\Http\SessionStoreInterface;
+use MintyPHP\Module\Notifications\Service\NotificationService;
+use MintyPHP\Router;
+use MintyPHP\Support\Guard;
+
+Guard::requireLogin();
+
+if (requestInput()->method() !== 'GET') {
+    http_response_code(405);
+    Router::json(['ok' => false, 'error' => 'method_not_allowed']);
+    return;
+}
+
+$session = app(SessionStoreInterface::class)->all();
+$userId = (int) ($session['user']['id'] ?? 0);
+if ($userId <= 0) {
+    http_response_code(401);
+    Router::json(['ok' => false, 'error' => 'unauthorized']);
+    return;
+}
+
+$service = app(NotificationService::class);
+$notifications = $service->listForUser($userId, 50);
+$unreadCount = $service->unreadCount($userId);
+
+app(SessionStoreInterface::class)->set('module.notifications.unread_count', $unreadCount);
+
+Router::json([
+    'ok' => true,
+    'notifications' => $notifications,
+    'unread_count' => $unreadCount,
+]);