feat(scheduler): dispatch event on job failure, notify admins via notifications module

Add ?ModuleEventDispatcher to SchedulerRunService (fail-open, nullable).
Dispatch scheduler.job_failed event when a job fails with payload:
job_id, job_key, label, error_code, error_message, trigger_type.

New SchedulerJobFailedNotificationListener in notifications module
creates in-app admin notifications for users with JOBS_MANAGE
permission, scoped per tenant, with 30-min dedup per job_key.

Also fixes audit module manifest: system_audit_purge job_key was
mismatched (audit_system_purge vs system_audit_purge in DB).

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

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

@@ -15,6 +15,7 @@ class NotificationService
         'user.activated' => true,
         'user.deactivated' => true,
         'user.assignment_changed' => true,
+        'scheduler.job_failed' => true,
     ];
 
     public function __construct(