b46691747c
Implement the central ConfigurationDatabase side of SMS notifications: - NotificationConfiguration: EmailAddress now nullable (SMS-only recipients carry a PhoneNumber, no email); add PhoneNumber nvarchar(32); add SmsConfigurationConfiguration (AuthToken sized as the encrypted column, mirroring SmtpConfiguration.Credentials; timeout/retry mapped REQUIRED for ctor-default round-trip fidelity). - ScadaBridgeDbContext: add SmsConfigurations DbSet, encrypt AuthToken at rest via EncryptedStringConverter, and cover SmsConfiguration in the schema-only secret-write guard. - NotificationRepository: implement the four INotificationRepository SMS-config methods (resolves the 4x CS0535), mirroring the SMTP methods' stage-only / separate-SaveChangesAsync discipline. - Migration AddSmsNotifications: idempotent (guarded) ALTER EmailAddress nullable, ADD PhoneNumber, CREATE SmsConfigurations; Down reverses cleanly (backfills NULL emails before restoring NOT NULL).