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).
Joseph Doherty