refactor: modify into client server model

Server/Program.cs

@@ -0,0 +1,35 @@
+using System.Net;
+using System.Net.Sockets;
+
+using var listener = new Socket(SocketType.Stream, ProtocolType.Tcp);
+listener.Bind(new IPEndPoint(IPAddress.Loopback, 9000));
+
+Console.WriteLine($"Listening on {listener.LocalEndPoint}");
+
+listener.Listen();
+
+while (true)
+{
+  var connection = await listener.AcceptAsync();
+
+  _ = Task.Run(async () =>
+    {
+
+      var buffer = new byte[4096];
+      try
+      {
+        while (true)
+        {
+          int read = await connection.ReceiveAsync(buffer, SocketFlags.None);
+          if (read == 0) break;
+
+          await connection.SendAsync(buffer[..read], SocketFlags.None);
+        }
+      }
+      finally
+      {
+        connection.Dispose();
+      }
+    }
+  );
+}