feat(di): register MediatR with service collection

src/WorkFlow.Application/DependencyInjection.cs

@@ -15,6 +15,10 @@ public static class DependencyInjection
         services.TryAddScoped<IProfileObjStateService, ProfileObjStateService>();
         services.TryAddScoped<IProfileService, ProfileService>();
         services.TryAddScoped<IStateService, StateService>();
+        services.AddMediatR(cfg =>
+        {
+            cfg.RegisterServicesFromAssembly(typeof(DependencyInjection).Assembly);
+        });
 
         return services;
     }