feat(admin): 新增管理员角色、账单、订阅、套餐管理功能

- 新增 AdminRolesController 实现角色 CRUD 和权限管理
- 新增 BillingsController 实现账单查询功能
- 新增 SubscriptionsController 实现订阅管理功能
- 新增 TenantPackagesController 实现套餐管理功能
- 新增租户详情、配额使用、账单列表等查询功能
- 新增 TenantPackage、TenantSubscription 等领域实体
- 新增相关枚举：SubscriptionStatus、TenantPackageType 等
- 更新 appsettings 配置文件
- 更新权限授权策略提供者

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

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

@@ -0,0 +1,59 @@
+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.Constants;
+using TakeoutSaaS.Shared.Abstractions.Exceptions;
+
+namespace TakeoutSaaS.Application.Identity.Handlers;
+
+/// <summary>
+/// 获取平台角色权限列表查询处理器。
+/// </summary>
+public sealed class GetAdminRolePermissionsQueryHandler(
+    IRoleRepository roleRepository,
+    IRolePermissionRepository rolePermissionRepository,
+    IPermissionRepository permissionRepository)
+    : IRequestHandler<GetAdminRolePermissionsQuery, IReadOnlyList<PermissionDto>>
+{
+    /// <inheritdoc />
+    public async Task<IReadOnlyList<PermissionDto>> Handle(GetAdminRolePermissionsQuery request, CancellationToken cancellationToken)
+    {
+        // 1. 校验角色存在
+        var role = await roleRepository.FindByIdAsync(PortalType.Admin, null, request.RoleId, cancellationToken)
+            ?? throw new BusinessException(ErrorCodes.NotFound, "角色不存在");
+
+        // 2. 查询角色权限关系
+        var rolePermissions = await rolePermissionRepository.GetByRoleIdsAsync(
+            PortalType.Admin,
+            null,
+            [request.RoleId],
+            cancellationToken);
+
+        // 3. 提取权限 ID 集合
+        var permissionIds = rolePermissions.Select(rp => rp.PermissionId).Distinct().ToArray();
+        if (permissionIds.Length == 0)
+        {
+            return [];
+        }
+
+        // 4. 查询权限详情
+        var permissions = await permissionRepository.GetByIdsAsync(permissionIds, cancellationToken);
+
+        // 5. 映射 DTO
+        return permissions
+            .Select(p => new PermissionDto
+            {
+                Portal = p.Portal,
+                Id = p.Id,
+                ParentId = p.ParentId,
+                SortOrder = p.SortOrder,
+                Type = p.Type,
+                Name = p.Name,
+                Code = p.Code,
+                Description = p.Description
+            })
+            .ToArray();
+    }
+}