Enhance Event admin UI and fix translations

- Remove default_locale and primary_join_token columns from event list
- Add read-only join link field to event edit form
- Add missing translations for used/remaining photos and join link
- Fix array-to-string conversion error in join link modal

resources/views/filament/events/join-link.blade.php

@@ -13,7 +13,7 @@
 <div {{ $stacked }}>
   <x-filament::section
     :heading="__('admin.events.join_link.event_label')"
-    :description="$event->name"
+    :description="is_array($event->name) ? ($event->name['de'] ?? collect($event->name)->first() ?? '') : $event->name"
     :icon="Heroicon::InformationCircle"
   >
     <x-slot name="afterHeader">