fix : 회원 관리 API 수정 및 ApiResponse 타입 수정

app/Models/Members/UserTenant.php

@@ -13,7 +13,26 @@ class UserTenant extends Model
     use SoftDeletes, ModelTrait, BelongsToTenant;
 
     protected $fillable = [
-        'user_id', 'tenant_id', 'is_active', 'joined_at', 'left_at'
+        'user_id', 'tenant_id', 'is_active', 'is_default', 'joined_at', 'left_at'
+    ];
+
+    protected $guarded = [
+        'id',
+        'created_at',
+        'updated_at',
+        'deleted_at',
+    ];
+
+    protected $casts = [
+        'joined_at'      => 'datetime',
+        'left_at'      => 'datetime',
+        'created_at'      => 'datetime',
+        'updated_at'      => 'datetime',
+        'deleted_at'      => 'datetime',
+    ];
+
+    protected $hidden = [
+        'deleted_at',
     ];
 
     public function user()