fix(siteruntime): decode List value to typed array before DCL write (OPC UA array write path)

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/InstanceActor.cs

@@ -431,11 +431,37 @@ public class InstanceActor : ReceiveActor
             return;
         }
 
+        // MV (C1): for a data-sourced List attribute the incoming command.Value is
+        // the canonical JSON array string (ScopeAccessors encodes the script's
+        // List<T> for transport/storage). Writing that string straight to the DCL
+        // would push a String scalar to an array node. Decode it back to a typed
+        // List<T> so the DCL/Variant write produces a real array. A non-empty value
+        // that fails to decode (malformed JSON / bad element) is poison — reject the
+        // write rather than forward garbage to the device (mirrors the static-path
+        // rejection in HandleSetStaticAttributeCore). Scalars are unchanged.
+        object? writeValue = command.Value;
+        if (IsListAttribute(resolved) && !string.IsNullOrWhiteSpace(command.Value))
+        {
+            var decoded = DecodeAttributeValue(resolved, command.Value);
+            if (decoded == null)
+            {
+                _logger.LogWarning(
+                    "SetAttribute rejected — value for data-sourced List attribute '{Attribute}' on instance '{Instance}' is not a valid list",
+                    attributeName, instanceName);
+                caller.Tell(new SetStaticAttributeResponse(
+                    correlationId, instanceName, attributeName, false,
+                    $"Invalid list value for attribute '{attributeName}'", DateTimeOffset.UtcNow));
+                return;
+            }
+
+            writeValue = decoded;
+        }
+
         var writeRequest = new WriteTagRequest(
             correlationId,
             resolved.BoundDataConnectionName!,
             resolved.DataSourceReference!,
-            command.Value,
+            writeValue,
             DateTimeOffset.UtcNow);
 
         // Ask the DCL and pipe the result back to the original caller. The DCL