feat: consume transactional email notifications

Add contract validation, SMTP delivery results, terminal failure context, neutral development seeding, and local Docker setup.

Ref: IT-1033

HrynCo.NotificationService.Worker.Services/ServiceCollectionExtensions.cs

@@ -11,6 +11,8 @@ public static class ServiceCollectionExtensions
         services.AddSingleton<IRabbitMqPublisher, RabbitMqPublisher>();
         services.AddScoped<IEmailTemplateService, EmailTemplateService>();
         services.AddScoped<IEmailTemplateRenderingService, EmailTemplateRenderingService>();
+        services.AddScoped<ISmtpEmailSender, SmtpEmailSender>();
+        services.AddScoped<INotificationResultPublisher, NotificationResultPublisher>();
         services.AddScoped<ISendEmailService, SendEmailService>();
         return services;
     }