feat: 实现动态租户解析与移除菜单回退逻辑

1. 新增 ITenantCodeResolver 接口和 DatabaseTenantCodeResolver 实现
2. 修改 TenantResolutionMiddleware 支持从数据库动态解析租户编码
3. ITenantRepository 新增 FindIdByCodeAsync 方法
4. 移除 EfMenuRepository 中危险的系统菜单回退逻辑
5. 调整服务注册顺序确保依赖正确注入

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

src/Infrastructure/TakeoutSaaS.Infrastructure/Identity/Repositories/EfMenuRepository.cs

@@ -2,65 +2,37 @@ using Microsoft.EntityFrameworkCore;
 using TakeoutSaaS.Domain.Identity.Entities;
 using TakeoutSaaS.Domain.Identity.Repositories;
 using TakeoutSaaS.Infrastructure.Identity.Persistence;
-using TakeoutSaaS.Shared.Abstractions.Tenancy;
 
 namespace TakeoutSaaS.Infrastructure.Identity.Repositories;
 
 /// <summary>
 /// 菜单仓储 EF 实现。
 /// </summary>
-public sealed class EfMenuRepository(IdentityDbContext dbContext, ITenantContextAccessor tenantContextAccessor) : IMenuRepository
+public sealed class EfMenuRepository(IdentityDbContext dbContext) : IMenuRepository
 {
     /// <inheritdoc />
     public async Task<IReadOnlyList<MenuDefinition>> GetByTenantAsync(long tenantId, CancellationToken cancellationToken = default)
     {
-        // 1. 优先返回租户自定义菜单
+        // 1. 仅返回该租户的菜单，无回退逻辑
         var tenantMenus = await dbContext.MenuDefinitions
             .AsNoTracking()
-            .Where(x => x.TenantId == tenantId)
+            .Where(x => x.TenantId == tenantId && x.DeletedAt == null)
             .OrderBy(x => x.ParentId)
             .ThenBy(x => x.SortOrder)
             .ToListAsync(cancellationToken);
-        if (tenantMenus.Count > 0)
-        {
-            return tenantMenus;
-        }
 
-        // 2. (空行后) 回退系统默认菜单（TenantId=0）
-        using (tenantContextAccessor.EnterTenantScope(0, "menu"))
-        {
-            var systemMenus = await dbContext.MenuDefinitions
-                .AsNoTracking()
-                .Where(x => x.TenantId == 0 && x.DeletedAt == null)
-                .OrderBy(x => x.ParentId)
-                .ThenBy(x => x.SortOrder)
-                .ToListAsync(cancellationToken);
-
-            return systemMenus;
-        }
+        return tenantMenus;
     }
 
     /// <inheritdoc />
     public async Task<MenuDefinition?> FindByIdAsync(long id, long tenantId, CancellationToken cancellationToken = default)
     {
-        // 1. 优先查租户菜单
-        var tenantMenu = await dbContext.MenuDefinitions
+        // 1. 仅查询该租户的菜单，无回退逻辑
+        return await dbContext.MenuDefinitions
             .AsNoTracking()
             .FirstOrDefaultAsync(
-                x => x.Id == id && x.TenantId == tenantId,
+                x => x.Id == id && x.TenantId == tenantId && x.DeletedAt == null,
                 cancellationToken);
-        if (tenantMenu != null)
-        {
-            return tenantMenu;
-        }
-
-        // 2. (空行后) 回退查系统默认菜单（TenantId=0）
-        using (tenantContextAccessor.EnterTenantScope(0, "menu"))
-        {
-            return await dbContext.MenuDefinitions
-                .AsNoTracking()
-                .FirstOrDefaultAsync(x => x.Id == id && x.TenantId == 0 && x.DeletedAt == null, cancellationToken);
-        }
     }
 
     /// <inheritdoc />