feat: add permission hierarchy tree

src/Domain/TakeoutSaaS.Domain/Identity/Entities/Permission.cs

@@ -7,6 +7,21 @@ namespace TakeoutSaaS.Domain.Identity.Entities;
 /// </summary>
 public sealed class Permission : MultiTenantEntityBase
 {
+    /// <summary>
+    /// 父级权限 ID，根节点为 0。
+    /// </summary>
+    public long ParentId { get; set; }
+
+    /// <summary>
+    /// 排序值，值越小越靠前。
+    /// </summary>
+    public int SortOrder { get; set; }
+
+    /// <summary>
+    /// 权限类型（group/leaf）。
+    /// </summary>
+    public string Type { get; set; } = "leaf";
+
     /// <summary>
     /// 权限名称。
     /// </summary>