fix(transport): transport template NativeAlarmSources — imports no longer amputate native alarm mirrors nor dangle instance overrides

New TemplateNativeAlarmSourceDto + init-only TemplateDto.NativeAlarmSources (empty
default, additive — IsInherited placeholders carried for the collision detector).
Exported in ToBundleContent, consumed in FromBundleContent + BuildTemplate, and a
new SyncTemplateNativeAlarmSourcesAsync runs the Overwrite add/update/delete child
sync with per-change audit rows. ArtifactDiff.CompareTemplate now DiffChildren over
native sources so Preview reports a NativeAlarmSources field change. Proven by an
end-to-end flatten test: an instance native-alarm-source override that dangled
pre-fix now resolves against the re-imported template source.

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

src/ZB.MOM.WW.ScadaBridge.Transport/Import/ArtifactDiff.cs

@@ -101,6 +101,15 @@ public sealed class ArtifactDiff
             "Compositions",
             changes);
 
+        DiffChildren(
+            existing.NativeAlarmSources,
+            incoming.NativeAlarmSources,
+            e => e.Name,
+            i => i.Name,
+            NativeAlarmSourcesEqual,
+            "NativeAlarmSources",
+            changes);
+
         return BuildItem("Template", incoming.Name, changes);
     }
 
@@ -665,6 +674,15 @@ public sealed class ArtifactDiff
         && e.ReturnDefinition == i.ReturnDefinition
         && e.IsLocked == i.IsLocked;
 
+    private static bool NativeAlarmSourcesEqual(TemplateNativeAlarmSource e, TemplateNativeAlarmSourceDto i) =>
+        e.Description == i.Description
+        && e.ConnectionName == i.ConnectionName
+        && e.SourceReference == i.SourceReference
+        && e.ConditionFilter == i.ConditionFilter
+        && e.IsLocked == i.IsLocked
+        && e.IsInherited == i.IsInherited
+        && e.LockedInDerived == i.LockedInDerived;
+
     private static bool ExternalSystemMethodsEqual(ExternalSystemMethod e, ExternalSystemMethodDto i) =>
         e.HttpMethod == i.HttpMethod
         && e.Path == i.Path