fix(transport): export instance AreaName — Area-by-name reconciliation was half-shipped (exporter hardcoded null)

Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj

src/ZB.MOM.WW.ScadaBridge.Transport/Export/BundleExporter.cs

@@ -1,4 +1,5 @@
 using System.Security.Cryptography;
+using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Options;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Services;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Transport;
@@ -72,6 +73,24 @@ public sealed class BundleExporter : IBundleExporter
         //    folder chain, transitive shared-scripts/external-systems if requested).
         var resolved = await _resolver.ResolveAsync(selection, cancellationToken).ConfigureAwait(false);
 
+        // 1b. Areas travel by NAME (the importer resolves-or-creates them under the
+        //     target site), so we only need an id→name lookup for the AreaIds the
+        //     exported instances actually reference — a single query over Areas keyed
+        //     to those FKs. Without this the serializer would emit AreaName: null and
+        //     the imported instance would lose its area assignment.
+        var referencedAreaIds = resolved.Instances
+            .Select(i => i.AreaId)
+            .Where(id => id is not null)
+            .Select(id => id!.Value)
+            .Distinct()
+            .ToList();
+        var areaNameById = referencedAreaIds.Count == 0
+            ? new Dictionary<int, string>()
+            : await _dbContext.Areas
+                .Where(a => referencedAreaIds.Contains(a.Id))
+                .ToDictionaryAsync(a => a.Id, a => a.Name, cancellationToken)
+                .ConfigureAwait(false);
+
         // 2. Convert to the wire-shaped DTO (strips EF identity, refs-by-name).
         //    The resolver's site/dataConnection/instance closure is wired
         //    through via object-initializer — without this the aggregate would
@@ -97,6 +116,9 @@ public sealed class BundleExporter : IBundleExporter
             // bundle ships an empty smsConfigs array even when SMS configs were
             // selected — mirrors the site/instance fix (review item I3).
             SmsConfigurations = resolved.SmsConfigs,
+            // Area id→name lookup for the exported instances — feeds the serializer's
+            // AreaName projection so each instance's area travels by name.
+            AreaNameById = areaNameById,
         };
         var contentDto = _entitySerializer.ToBundleContent(aggregate);