feat(audit): M5.2 per-node stuck-count KPIs (T6) — repo per-node aggregation, actor message pair, CentralUI tiles

src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Notification/NotificationOutboxQueries.cs

@@ -159,3 +159,23 @@ public record PerSiteNotificationKpiResponse(
     bool Success,
     string? ErrorMessage,
     IReadOnlyList<SiteNotificationKpiSnapshot> Sites);
+
+/// <summary>
+/// Outbox UI -> Central: request for the per-node notification outbox KPI breakdown.
+/// Mirrors <see cref="PerSiteNotificationKpiRequest"/> but groups by <c>SourceNode</c>
+/// instead of <c>SourceSiteId</c>. Additive — does not change per-site behaviour.
+/// </summary>
+public record PerNodeNotificationKpiRequest(
+    string CorrelationId);
+
+/// <summary>
+/// Central -> Outbox UI: per-node KPI breakdown for the Notification KPIs page.
+/// On a repository fault <see cref="Success"/> is <c>false</c>, <see cref="ErrorMessage"/>
+/// carries the cause, and <see cref="Nodes"/> is empty. Nodes with a <c>NULL</c>
+/// <c>SourceNode</c> are omitted.
+/// </summary>
+public record PerNodeNotificationKpiResponse(
+    string CorrelationId,
+    bool Success,
+    string? ErrorMessage,
+    IReadOnlyList<NodeNotificationKpiSnapshot> Nodes);