feat: 实现租户角色列表查询和删除接口

- 获取租户角色列表：GET /api/admin/v1/tenants/{tenantId}/roles
- 删除租户角色：DELETE /api/admin/v1/tenants/{tenantId}/roles/{roleId}

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

src/Application/TakeoutSaaS.Application/Identity/Commands/DeleteTenantRoleCommand.cs

@@ -0,0 +1,19 @@
+using MediatR;
+
+namespace TakeoutSaaS.Application.Identity.Commands;
+
+/// <summary>
+/// 删除租户角色命令。
+/// </summary>
+public sealed record DeleteTenantRoleCommand : IRequest<bool>
+{
+    /// <summary>
+    /// 租户 ID（由路由绑定）。
+    /// </summary>
+    public long TenantId { get; init; }
+
+    /// <summary>
+    /// 角色 ID（由路由绑定）。
+    /// </summary>
+    public long RoleId { get; init; }
+}

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

@@ -0,0 +1,33 @@
+using MediatR;
+using TakeoutSaaS.Application.Identity.Commands;
+using TakeoutSaaS.Domain.Identity.Enums;
+using TakeoutSaaS.Domain.Identity.Repositories;
+using TakeoutSaaS.Shared.Abstractions.Constants;
+using TakeoutSaaS.Shared.Abstractions.Exceptions;
+
+namespace TakeoutSaaS.Application.Identity.Handlers;
+
+/// <summary>
+/// 删除租户角色命令处理器。
+/// </summary>
+public sealed class DeleteTenantRoleCommandHandler(IRoleRepository roleRepository)
+    : IRequestHandler<DeleteTenantRoleCommand, bool>
+{
+    /// <inheritdoc />
+    public async Task<bool> Handle(DeleteTenantRoleCommand request, CancellationToken cancellationToken)
+    {
+        // 1. 校验角色存在
+        var role = await roleRepository.FindByIdAsync(PortalType.Tenant, request.TenantId, request.RoleId, cancellationToken);
+        if (role is null)
+        {
+            throw new BusinessException(ErrorCodes.NotFound, "角色不存在");
+        }
+
+        // 2. 执行软删除
+        await roleRepository.DeleteAsync(PortalType.Tenant, request.TenantId, request.RoleId, cancellationToken);
+        await roleRepository.SaveChangesAsync(cancellationToken);
+
+        // 3. 返回成功
+        return true;
+    }
+}

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

@@ -0,0 +1,48 @@
+using MediatR;
+using TakeoutSaaS.Application.Identity.Contracts;
+using TakeoutSaaS.Application.Identity.Queries;
+using TakeoutSaaS.Domain.Identity.Enums;
+using TakeoutSaaS.Domain.Identity.Repositories;
+using TakeoutSaaS.Shared.Abstractions.Results;
+
+namespace TakeoutSaaS.Application.Identity.Handlers;
+
+/// <summary>
+/// 获取租户角色列表查询处理器。
+/// </summary>
+public sealed class ListTenantRolesQueryHandler(IRoleRepository roleRepository)
+    : IRequestHandler<ListTenantRolesQuery, PagedResult<RoleDto>>
+{
+    /// <inheritdoc />
+    public async Task<PagedResult<RoleDto>> Handle(ListTenantRolesQuery request, CancellationToken cancellationToken)
+    {
+        // 1. 查询租户下所有角色
+        var roles = await roleRepository.SearchAsync(PortalType.Tenant, request.TenantId, request.Keyword, cancellationToken);
+
+        // 2. 计算分页参数
+        var totalCount = roles.Count;
+        var page = Math.Max(1, request.Page);
+        var pageSize = Math.Clamp(request.PageSize, 1, 100);
+
+        // 3. 应用分页
+        var pagedRoles = roles
+            .OrderBy(r => r.Code)
+            .Skip((page - 1) * pageSize)
+            .Take(pageSize)
+            .ToArray();
+
+        // 4. 映射 DTO
+        var dtos = pagedRoles.Select(role => new RoleDto
+        {
+            Portal = role.Portal,
+            Id = role.Id,
+            TenantId = role.TenantId,
+            Code = role.Code,
+            Name = role.Name,
+            Description = role.Description
+        }).ToArray();
+
+        // 5. 返回分页结果
+        return new PagedResult<RoleDto>(dtos, page, pageSize, totalCount);
+    }
+}

src/Application/TakeoutSaaS.Application/Identity/Queries/ListTenantRolesQuery.cs

@@ -0,0 +1,31 @@
+using MediatR;
+using TakeoutSaaS.Application.Identity.Contracts;
+using TakeoutSaaS.Shared.Abstractions.Results;
+
+namespace TakeoutSaaS.Application.Identity.Queries;
+
+/// <summary>
+/// 获取租户角色列表查询。
+/// </summary>
+public sealed record ListTenantRolesQuery : IRequest<PagedResult<RoleDto>>
+{
+    /// <summary>
+    /// 租户 ID。
+    /// </summary>
+    public long TenantId { get; init; }
+
+    /// <summary>
+    /// 关键字（角色名称/编码）。
+    /// </summary>
+    public string? Keyword { get; init; }
+
+    /// <summary>
+    /// 页码（从 1 开始）。
+    /// </summary>
+    public int Page { get; init; } = 1;
+
+    /// <summary>
+    /// 每页条数。
+    /// </summary>
+    public int PageSize { get; init; } = 20;
+}