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/Entities/Notifications/NotificationList.cs

@@ -0,0 +1,13 @@
+namespace ScadaLink.Commons.Entities.Notifications;
+
+public class NotificationList
+{
+    public int Id { get; set; }
+    public string Name { get; set; }
+    public ICollection<NotificationRecipient> Recipients { get; set; } = new List<NotificationRecipient>();
+
+    public NotificationList(string name)
+    {
+        Name = name ?? throw new ArgumentNullException(nameof(name));
+    }
+}

src/ScadaLink.Commons/Entities/Notifications/NotificationRecipient.cs

@@ -0,0 +1,15 @@
+namespace ScadaLink.Commons.Entities.Notifications;
+
+public class NotificationRecipient
+{
+    public int Id { get; set; }
+    public int NotificationListId { get; set; }
+    public string Name { get; set; }
+    public string EmailAddress { get; set; }
+
+    public NotificationRecipient(string name, string emailAddress)
+    {
+        Name = name ?? throw new ArgumentNullException(nameof(name));
+        EmailAddress = emailAddress ?? throw new ArgumentNullException(nameof(emailAddress));
+    }
+}

src/ScadaLink.Commons/Entities/Notifications/SmtpConfiguration.cs

@@ -0,0 +1,23 @@
+namespace ScadaLink.Commons.Entities.Notifications;
+
+public class SmtpConfiguration
+{
+    public int Id { get; set; }
+    public string Host { get; set; }
+    public int Port { get; set; }
+    public string AuthType { get; set; }
+    public string? Credentials { get; set; }
+    public string? TlsMode { get; set; }
+    public string FromAddress { get; set; }
+    public int ConnectionTimeoutSeconds { get; set; }
+    public int MaxConcurrentConnections { get; set; }
+    public int MaxRetries { get; set; }
+    public TimeSpan RetryDelay { get; set; }
+
+    public SmtpConfiguration(string host, string authType, string fromAddress)
+    {
+        Host = host ?? throw new ArgumentNullException(nameof(host));
+        AuthType = authType ?? throw new ArgumentNullException(nameof(authType));
+        FromAddress = fromAddress ?? throw new ArgumentNullException(nameof(fromAddress));
+    }
+}