fix: resolve permission toggle persistence, nudge terminology, and bulk action bugs (Bugs #2-5)

- Fix togglePermission() to always include all permission keys with false defaults
- Add migration to backfill null/empty Manager permissions with config defaults
- Rename nudge UI text from "Relance" to "Notification"/"Notifier" across 8 files
- Fix select-all checkbox and show checkboxes on all declaration rows
- Remove en_attente_client status restriction from BulkNotificationController

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

app/Enums/NotificationType.php

@@ -16,6 +16,8 @@ final class NotificationType extends Enum
 
     const StatusChanged = 'status_changed';
 
+    const Mention = 'mention';
+
     /**
      * Get French display labels for each notification type.
      *
@@ -24,11 +26,12 @@ final class NotificationType extends Enum
     public static function labels(): array
     {
         return [
-            self::Nudge => 'Relance',
+            self::Nudge => 'Notification',
             self::DeclarationOverdue => 'Déclaration en retard',
             self::DocumentUploaded => 'Document téléversé',
             self::BulkNotification => 'Notification groupée',
             self::StatusChanged => 'Statut modifié',
+            self::Mention => 'Mention',
         ];
     }
 }