Refactor backend and frontend modules for architecture alignment

backend/src/main/java/com/yoyuzh/admin/AdminRegistrationInviteCodeUpdateRequest.java

@@ -0,0 +1,11 @@
+package com.yoyuzh.admin;
+
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
+
+public record AdminRegistrationInviteCodeUpdateRequest(
+        @NotBlank(message = "邀请码不能为空")
+        @Size(max = 64, message = "邀请码长度不能超过 64 个字符")
+        String inviteCode
+) {
+}