refactor: 将 Permission 和 MenuDefinition 改为系统级实体

- Permission 和 MenuDefinition 改为继承 AuditableEntityBase（移除 TenantId）
- 添加 PortalType 枚举区分平台端/租户端
- Repository 使用 IgnoreQueryFilters() 查询系统级数据
- 更新所有相关 Handler 和 DTO，移除 TenantId 引用
- 与 AdminApi 保持一致的设计

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Application/TakeoutSaaS.Application/Identity/Handlers/UpdateMenuCommandHandler.cs

@@ -5,16 +5,13 @@ using TakeoutSaaS.Application.Identity.Contracts;
 using TakeoutSaaS.Domain.Identity.Repositories;
 using TakeoutSaaS.Shared.Abstractions.Constants;
 using TakeoutSaaS.Shared.Abstractions.Exceptions;
-using TakeoutSaaS.Shared.Abstractions.Tenancy;
 
 namespace TakeoutSaaS.Application.Identity.Handlers;
 
 /// <summary>
 /// 更新菜单处理器。
 /// </summary>
-public sealed class UpdateMenuCommandHandler(
-    IMenuRepository menuRepository,
-    ITenantProvider tenantProvider)
+public sealed class UpdateMenuCommandHandler(IMenuRepository menuRepository)
     : IRequestHandler<UpdateMenuCommand, MenuDefinitionDto?>
 {
     /// <inheritdoc />
@@ -27,8 +24,7 @@ public sealed class UpdateMenuCommandHandler(
         }
 
         // 2. 校验存在
-        var tenantId = tenantProvider.GetCurrentTenantId();
-        var entity = await menuRepository.FindByIdAsync(request.Id, tenantId, cancellationToken)
+        var entity = await menuRepository.FindByIdAsync(request.Id, cancellationToken)
             ?? throw new BusinessException(ErrorCodes.NotFound, "菜单不存在");
 
         // 3. 更新字段