fix(audit): harden module isolation and fix post-extraction drift

Fix 5 broken FQCN references (runtime errors) where core pages referenced
non-existent MintyPHP\Service\Audit\AuditMetadataEnricher and SystemAuditService.
Add AuditMetadataEnricherInterface with NullAuditMetadataEnricher fallback so
deactivating the audit module no longer crashes core edit pages.

Move audit search resources from core Search*Provider files into the module
via a new AuditSearchResourceProvider implementing the existing
SearchResourceProvider contract. Add module-specific purge permissions
(audit.api.purge, audit.imports.purge) replacing core ABILITY_ADMIN_SETTINGS_UPDATE.

Also fixes: session key prefix convention, hardcoded English string, $_SERVER
superglobal fallback, and manifest schema drift (i18n_path, group in ui_slots).

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

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

@@ -3,8 +3,9 @@
 namespace MintyPHP\Module\Audit\Service;
 
 use MintyPHP\Repository\User\UserReadRepositoryInterface;
+use MintyPHP\Service\Audit\AuditMetadataEnricherInterface;
 
-class AuditMetadataEnricher
+class AuditMetadataEnricher implements AuditMetadataEnricherInterface
 {
     public function __construct(
         private readonly UserReadRepositoryInterface $userReadRepository