feat(member): add message reach backend module and docs seeds

src/Domain/TakeoutSaaS.Domain/Membership/Enums/MemberMessageRecipientStatus.cs

@@ -0,0 +1,23 @@
+namespace TakeoutSaaS.Domain.Membership.Enums;
+
+/// <summary>
+/// 消息收件明细发送状态。
+/// </summary>
+public enum MemberMessageRecipientStatus
+{
+    /// <summary>
+    /// 待发送。
+    /// </summary>
+    Pending = 0,
+
+    /// <summary>
+    /// 发送成功。
+    /// </summary>
+    Sent = 1,
+
+    /// <summary>
+    /// 发送失败。
+    /// </summary>
+    Failed = 2
+}
+