fix: always wrap responses in ApiResponse<T>

Success responses now use ApiResponse<T>{ Success=true, Data=T }
instead of returning raw T — consistent shape for all outcomes.

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

HrynCo.NotificationService.Api/Controllers/EmailTemplates/EmailTemplatesController.cs

@@ -1,3 +1,4 @@
+using HrynCo.NotificationService.Api.Infrastructure;
 using HrynCo.NotificationService.Services.EmailTemplates.Create;
 using HrynCo.NotificationService.Services.EmailTemplates.Delete;
 using HrynCo.NotificationService.Services.EmailTemplates.Get;
@@ -48,7 +49,7 @@ public sealed class EmailTemplatesController : ApiControllerBase
         return CreatedAtAction(
             nameof(Get),
             new { serviceName = request.ServiceName, key = request.Key, languageCode = request.LanguageCode },
-            result.Result
+            new ApiResponse<Guid> { Success = true, Data = result.Result }
         );
     }