Add project files.

AOC.Shared/AOCAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace AOC.Shared
+{
+	public class ProblemInfoAttribute : Attribute
+	{
+		public int Day { get; init; }
+		public string Year { get; init; }
+		public string Name { get; init; }
+		public ProblemInfoAttribute(string year, int day, string name) {
+			Year = year;
+			Day = day;
+			Name = name;
+		}
+	}
+}