Ensure proper disposal and add HttpExtensions class

Updated `InvokeRecActionCommand.cs` to use `using` statements for `HttpClient`, `HttpRequestMessage`, and `HttpResponseMessage` to prevent resource leaks.

Added a new `HttpExtensions.cs` file with a static `HttpExtensions` class as a placeholder for future HTTP-related extension methods. Included necessary `using` directives for potential LINQ, collections, and asynchronous programming.

src/ReC.Application/Common/HttpExtensions.cs

@@ -0,0 +1,11 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ReC.Application.Common;
+
+public static class HttpExtensions
+{
+}