Make ActionId a required field across DTOs and entities

Updated the `RecActionDto`, `RecAction`, and `InvokeRecActionCommandHandler` to enforce `ActionId` as a required field. This change improves data integrity by removing nullable `ActionId` properties and eliminates the need for null checks or null-forgiveness operators.

src/ReC.Application/RecActions/Commands/InvokeRecActionCommand.cs

@@ -61,7 +61,7 @@ public class InvokeRecActionCommandHandler(
 
         await sender.Send(new CreateOutResCommand
         {
-            ActionId = (long) request.ActionId!,
+            ActionId = request.ActionId,
             Header = JsonSerializer.Serialize(resHeaders, options: new() { WriteIndented = false }),
             Body = resBody,
             AddedWho = config?["AddedWho"]