fix(store-and-forward): standby applies Add/Park/Requeue as upserts so a lost Add self-heals

src/ZB.MOM.WW.ScadaBridge.StoreAndForward/ReplicationService.cs

@@ -101,6 +101,13 @@ public class ReplicationService
     /// <summary>
     /// Applies a replicated operation received from the active node.
     /// Used by the standby node to keep its SQLite in sync.
+    ///
+    /// Add/Park/Requeue are applied as <b>upserts</b> (<see cref="StoreAndForwardStorage.UpsertMessageAsync"/>),
+    /// not blind INSERT/UPDATE: the full message rides in every one of those operations,
+    /// so a Park/Requeue whose original Add was lost (fire-and-forget replication is
+    /// best-effort) self-heals by materialising the row, and a duplicate Add (e.g.
+    /// re-issued by an anti-entropy resync) applies newest-wins instead of throwing a
+    /// primary-key violation. Remove is a plain delete.
     /// </summary>
     /// <param name="operation">The replication operation to apply.</param>
     /// <param name="storage">The standby node's store-and-forward storage to update.</param>
@@ -112,7 +119,7 @@ public class ReplicationService
         switch (operation.OperationType)
         {
             case ReplicationOperationType.Add when operation.Message != null:
-                await storage.EnqueueAsync(operation.Message);
+                await storage.UpsertMessageAsync(operation.Message);
                 break;
 
             case ReplicationOperationType.Remove:
@@ -121,13 +128,13 @@ public class ReplicationService
 
             case ReplicationOperationType.Park when operation.Message != null:
                 operation.Message.Status = StoreAndForwardMessageStatus.Parked;
-                await storage.UpdateMessageAsync(operation.Message);
+                await storage.UpsertMessageAsync(operation.Message);
                 break;
 
             case ReplicationOperationType.Requeue when operation.Message != null:
                 operation.Message.Status = StoreAndForwardMessageStatus.Pending;
                 operation.Message.RetryCount = 0;
-                await storage.UpdateMessageAsync(operation.Message);
+                await storage.UpsertMessageAsync(operation.Message);
                 break;
         }
     }