feat(notification-outbox): add NotificationOutboxOptions and delivery adapter abstraction

src/ScadaLink.NotificationOutbox/NotificationOutboxOptions.cs

@@ -0,0 +1,26 @@
+namespace ScadaLink.NotificationOutbox;
+
+/// <summary>
+/// Configuration options for the Notification Outbox component: dispatch cadence,
+/// batch sizing, stuck-message detection, terminal retention, and KPI windowing.
+/// </summary>
+public class NotificationOutboxOptions
+{
+    /// <summary>Interval between dispatch sweeps that pick up pending notifications for delivery.</summary>
+    public TimeSpan DispatchInterval { get; set; } = TimeSpan.FromSeconds(10);
+
+    /// <summary>Maximum number of notifications claimed for delivery in a single dispatch sweep.</summary>
+    public int DispatchBatchSize { get; set; } = 100;
+
+    /// <summary>Age past which an in-progress notification is considered stuck and re-claimed.</summary>
+    public TimeSpan StuckAgeThreshold { get; set; } = TimeSpan.FromMinutes(10);
+
+    /// <summary>Retention period for notifications in a terminal state before they are purged.</summary>
+    public TimeSpan TerminalRetention { get; set; } = TimeSpan.FromDays(365);
+
+    /// <summary>Interval between background purge sweeps of terminal notifications.</summary>
+    public TimeSpan PurgeInterval { get; set; } = TimeSpan.FromDays(1);
+
+    /// <summary>Trailing window used to compute the delivered-notifications throughput KPI.</summary>
+    public TimeSpan DeliveredKpiWindow { get; set; } = TimeSpan.FromMinutes(1);
+}