Phase 0 WP-0.2–0.9: Implement Commons (types, entities, interfaces, messages, protocol, tests)

- WP-0.2: Namespace/folder skeleton (26 directories)
- WP-0.3: Shared data types (6 enums, RetryPolicy, Result<T>)
- WP-0.4: 24 domain entity POCOs across 10 domain areas
- WP-0.5: 7 repository interfaces with full CRUD signatures
- WP-0.6: IAuditService cross-cutting interface
- WP-0.7: 26 message contract records across 8 concern areas
- WP-0.8: IDataConnection protocol abstraction with batch ops
- WP-0.9: 8 architectural constraint enforcement tests
All 40 tests pass, zero warnings.

src/ScadaLink.Commons/Interfaces/Repositories/INotificationRepository.cs

@@ -0,0 +1,30 @@
+using ScadaLink.Commons.Entities.Notifications;
+
+namespace ScadaLink.Commons.Interfaces.Repositories;
+
+public interface INotificationRepository
+{
+    // NotificationList
+    Task<NotificationList?> GetNotificationListByIdAsync(int id, CancellationToken cancellationToken = default);
+    Task<IReadOnlyList<NotificationList>> GetAllNotificationListsAsync(CancellationToken cancellationToken = default);
+    Task<NotificationList?> GetListByNameAsync(string name, CancellationToken cancellationToken = default);
+    Task AddNotificationListAsync(NotificationList list, CancellationToken cancellationToken = default);
+    Task UpdateNotificationListAsync(NotificationList list, CancellationToken cancellationToken = default);
+    Task DeleteNotificationListAsync(int id, CancellationToken cancellationToken = default);
+
+    // NotificationRecipient
+    Task<NotificationRecipient?> GetRecipientByIdAsync(int id, CancellationToken cancellationToken = default);
+    Task<IReadOnlyList<NotificationRecipient>> GetRecipientsByListIdAsync(int notificationListId, CancellationToken cancellationToken = default);
+    Task AddRecipientAsync(NotificationRecipient recipient, CancellationToken cancellationToken = default);
+    Task UpdateRecipientAsync(NotificationRecipient recipient, CancellationToken cancellationToken = default);
+    Task DeleteRecipientAsync(int id, CancellationToken cancellationToken = default);
+
+    // SmtpConfiguration
+    Task<SmtpConfiguration?> GetSmtpConfigurationByIdAsync(int id, CancellationToken cancellationToken = default);
+    Task<IReadOnlyList<SmtpConfiguration>> GetAllSmtpConfigurationsAsync(CancellationToken cancellationToken = default);
+    Task AddSmtpConfigurationAsync(SmtpConfiguration configuration, CancellationToken cancellationToken = default);
+    Task UpdateSmtpConfigurationAsync(SmtpConfiguration configuration, CancellationToken cancellationToken = default);
+    Task DeleteSmtpConfigurationAsync(int id, CancellationToken cancellationToken = default);
+
+    Task<int> SaveChangesAsync(CancellationToken cancellationToken = default);
+}