重构项目结构，移除Assignment相关功能，优化Submission模块

Entities/DTO/User/UserForAdmin.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Entities.DTO
+{
+	public record UserForAdmin
+	{
+		public string Email { get; init; }
+		public string SchoolName { get; init; }
+		public string Password { get; init; }
+		public string DisplayName { get; init; }
+		public string Address { get; init; }
+	}
+}