perf(historian): group-commit batch append on the historization outbox

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/Historian/IHistorizationOutbox.cs

@@ -19,6 +19,17 @@ public interface IHistorizationOutbox : IDisposable
     /// <returns>A task that represents the asynchronous operation.</returns>
     ValueTask AppendAsync(HistorizationOutboxEntry entry, CancellationToken ct);
 
+    /// <summary>
+    ///     Appends a burst of entries with ONE durability commit for the whole batch (group
+    ///     commit). Under PerEntry commit mode this is the per-batch fsync that replaces N
+    ///     per-entry fsyncs; under Periodic it is indistinguishable from N AppendAsync calls.
+    ///     An empty list is a no-op.
+    /// </summary>
+    /// <param name="entries">The value records to buffer, in append (FIFO) order.</param>
+    /// <param name="ct">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    ValueTask AppendBatchAsync(IReadOnlyList<HistorizationOutboxEntry> entries, CancellationToken ct);
+
     /// <summary>
     ///     Returns up to <paramref name="max"/> oldest un-acked entries in FIFO order without removing
     ///     them. Removal happens via <see cref="RemoveAsync"/> once each entry is durably written.