095361b73f
S1 made NotificationRecipient.EmailAddress nullable + added SmsConfiguration and four INotificationRepository SMS methods, breaking compilation beyond the intentionally-deferred central NotificationRepository. Fix 1 (CS8620/CS8604 nullable EmailAddress projections, email-only paths): - NotificationOutbox EmailNotificationDeliveryAdapter: filter non-null emails - DeploymentManager ArtifactDeploymentService: filter non-null emails - Transport EntitySerializer: filter non-null emails into NotificationRecipientDto Fix 2 (CS0535): stub the four SMS-config methods on SiteRuntime SiteNotificationRepository (central-only — NotSupportedException, matching the existing 'Managed via artifact deployment from Central' write-path pattern). Doc nits: reword NotificationRecipient private ctor and SmsConfiguration.AuthToken comments. The central ConfigurationDatabase.NotificationRepository compile break is left as-is (S2 implements those four methods).