Add HeaderQueryBehavior and update DI configuration

Added `HeaderQueryBehavior<TRecAction>` to handle header query
processing in the MediatR pipeline. Updated the `DependencyInjection`
class to register `HeaderQueryBehavior<>` alongside
`BodyQueryBehavior<>` in the MediatR configuration. The new behavior
currently throws a `NotImplementedException` as its logic is pending
implementation.

src/ReC.Application/DependencyInjection.cs

@@ -26,7 +26,7 @@ public static class DependencyInjection
         services.AddMediatR(cfg =>
         {
             cfg.RegisterServicesFromAssembly(Assembly.GetExecutingAssembly());
-            cfg.AddOpenBehaviors([typeof(BodyQueryBehavior<>)]);
+            cfg.AddOpenBehaviors([typeof(BodyQueryBehavior<>), typeof(HeaderQueryBehavior<>)]);
             cfg.LicenseKey = configOpt.LuckyPennySoftwareLicenseKey;
         });
 

src/ReC.Application/RecActions/Behaviors/HeaderQueryBehavior.cs

@@ -0,0 +1,15 @@
+using MediatR;
+using ReC.Application.Common.Dto;
+
+namespace ReC.Application.RecActions.Behaviors
+{
+    public class HeaderQueryBehavior<TRecAction> : IPipelineBehavior<TRecAction, Unit>
+        where TRecAction : RecActionDto
+    {
+        public Task<Unit> Handle(TRecAction action, RequestHandlerDelegate<Unit> next, CancellationToken cancel)
+        {
+            // Logic to process the header query can be added here
+            throw new NotImplementedException("HeaderQueryBehavior is not implemented yet.");
+        }
+    }
+}