Resolve all 46 low-severity architecture review findings

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/RealOpcUaClient.cs

@@ -675,9 +675,16 @@ public class RealOpcUaClient : IOpcUaClient
         List<DataShard> touched,
         CancellationToken cancellationToken)
     {
-        foreach (var (index, nodeId, startNode) in resolved)
+        // Plan once for this chunk while the apply gate keeps shard occupancy stable.
+        var placement = MonitoredItemShardPlanner.Plan(
+            _dataShards.Select(s => s.ItemCount).ToArray(), ItemsPerShard, resolved.Count);
+        for (var itemIndex = 0; itemIndex < resolved.Count; itemIndex++)
         {
-            var shard = await PlaceOnDataShardAsync(cancellationToken);
+            var (index, nodeId, startNode) = resolved[itemIndex];
+            var shardIndex = placement[itemIndex];
+            var shard = shardIndex < _dataShards.Count
+                ? _dataShards[shardIndex]
+                : await CreateDataShardAsync(cancellationToken);
             var handle = Guid.NewGuid().ToString();
             var monitoredItem = new MonitoredItem(shard.Subscription.DefaultItem)
             {
@@ -760,20 +767,6 @@ public class RealOpcUaClient : IOpcUaClient
             created.Count);
     }
 
-    /// <summary>
-    /// Returns the shard this item belongs on per
-    /// <see cref="MonitoredItemShardPlanner"/> — first shard with free capacity, else a
-    /// freshly created one. Callers must hold <see cref="_applyGate"/>.
-    /// </summary>
-    private async Task<DataShard> PlaceOnDataShardAsync(CancellationToken cancellationToken)
-    {
-        var index = MonitoredItemShardPlanner.Plan(
-            _dataShards.Select(s => s.ItemCount).ToList(), ItemsPerShard, 1)[0];
-        return index < _dataShards.Count
-            ? _dataShards[index]
-            : await CreateDataShardAsync(cancellationToken);
-    }
-
     /// <summary>
     /// Drops a monitored item that failed to create from the shard it was placed on.
     /// Callers must hold <see cref="_applyGate"/>. No ApplyChanges is issued: the server