refactor: 重新调整后端工程结构

server/src/Common/String.cs

@@ -0,0 +1,20 @@
+namespace Common;
+
+/// <summary>
+/// 字符串处理工具
+/// </summary>
+public class String
+{
+    /// <summary>
+    /// 反转字符串
+    /// </summary>
+    /// <param name="s">输入的字符串</param>
+    /// <returns>反转后的字符串</returns>
+    public static string Reverse(string s)
+    {
+        char[] charArray = s.ToCharArray();
+        Array.Reverse(charArray);
+        return new string(charArray);
+    }
+
+}