feat: admin audit logging across all admin actions

- AdminLogger: JSON-lines → /var/log/xamxam.log (prod) / storage/logs/admin.log (dev)
  + best-effort DB mirror to admin_audit_log table
- DB: admin_audit_log table, share_links.is_archived column
- ShareLink: archive() replaces delete(), toggleActive() returns new state,
  listActive()/listArchived() split, validateLink blocks archived slugs
- All action handlers wired: publish, unpublish, visibility, delete, csv/db export,
  tfe add/edit, tags, pages, apropos, form-help, access-request, maintenance,
  settings (formulaire toggles, objet types, smtp update), smtp-test
- acces.php: archive button replaces delete; collapsible archived links section
- setup-server.sh: provision /var/log/xamxam.log (www-data:xamxam 640)

app/public/admin/actions/export-csv.php

@@ -10,8 +10,11 @@ require_once __DIR__ . '/../../../src/AdminAuth.php';
 AdminAuth::requireLogin();
 
 require_once APP_ROOT . '/src/Controllers/ExportController.php';
+require_once APP_ROOT . '/src/AdminLogger.php';
 $controller = ExportController::create();
 
+AdminLogger::make()->logCsvExport();
+
 $filename = 'xamxam-export-' . date('Y-m-d') . '.csv';
 
 header('Content-Type: text/csv; charset=UTF-8');