What: Upgrade Filament auf v5.2.1 (inkl. composer.lock + veröffentlichte Filament assets unter public), SpecKit-Doku unter specs/102-..., plus kleine Anpassungen in Tests + Tenant-Scoping in BackupSetResource.
Verification: vendor/bin/sail bin pint --dirty --format agent (pass) + vendor/bin/sail artisan test --compact [AlertDeliveryViewerTest.php](http://_vscodecontentref_/6) tests/Feature/Filament/BackupSetGraphSafetyTest.php (pass)
Co-authored-by: Ahmed Darrazi <ahmed.darrazi@live.de>
Reviewed-on: #124
