refactor(audit): decouple API audit classes from core via interfaces

Core code (lib/) no longer imports any MintyPHP\Module\Audit\* classes directly.
New ApiAuditServiceInterface and ApiSystemAuditReporterInterface follow the
existing pattern (interface + null implementation in core, concrete binding
from module registrar). DoctorRunner and helpers/app.php now resolve through
DI interfaces, ensuring the audit module remains fully optional.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

modules/audit/lib/Module/Audit/Service/ApiAuditService.php

@@ -6,8 +6,9 @@ use MintyPHP\Http\ApiAuth;
 use MintyPHP\Http\RequestContext;
 use MintyPHP\Http\RequestRuntimeInterface;
 use MintyPHP\Module\Audit\Repository\ApiAuditLogRepository;
+use MintyPHP\Service\Audit\ApiAuditServiceInterface;
 
-class ApiAuditService
+class ApiAuditService implements ApiAuditServiceInterface
 {
     private const RETENTION_DAYS = 90;
     private const MAX_QUERY_KEYS = 30;