fix(deploy): include ElementDataType in RevisionHashService.HashableAttribute (#290)

Fold a List attribute's ElementDataType into the hashable projection so a
change to the element type (e.g. Int32 -> Double) with identical JSON-encoded
values is detected as a staleness/revision change. Inserted in alphabetical
position; null ElementDataType (scalars) is omitted by the canonical
serializer (WhenWritingNull), so scalar-only configs hash identically to
before. DiffService.AttributesEqual gains the same comparison to keep the
structured diff in parity with the staleness hash. Adds tests for differing
vs. equal ElementDataType (hash + diff) and the scalar no-op guard.

tests/ZB.MOM.WW.ScadaBridge.TemplateEngine.Tests/Flattening/DiffServiceTests.cs

@@ -162,6 +162,37 @@ public class DiffServiceTests
         Assert.Equal(DiffChangeType.Changed, diff.AttributeChanges[0].ChangeType);
     }
 
+    [Fact]
+    public void ComputeDiff_AttributeElementDataTypeChange_DetectedAsChanged()
+    {
+        // #290: ElementDataType is part of the revision hash, so AttributesEqual
+        // must also compare it — a List element-type change (Int32 → Double) with
+        // identical JSON-encoded values must surface as a Changed attribute,
+        // keeping the structured diff in parity with the staleness hash.
+        var oldConfig = new FlattenedConfiguration
+        {
+            InstanceUniqueName = "Instance1",
+            Attributes =
+            [
+                new ResolvedAttribute { CanonicalName = "Readings", Value = "[1,2]", DataType = "List", ElementDataType = "Int32" }
+            ]
+        };
+        var newConfig = new FlattenedConfiguration
+        {
+            InstanceUniqueName = "Instance1",
+            Attributes =
+            [
+                new ResolvedAttribute { CanonicalName = "Readings", Value = "[1,2]", DataType = "List", ElementDataType = "Double" }
+            ]
+        };
+
+        var diff = _sut.ComputeDiff(oldConfig, newConfig);
+
+        Assert.True(diff.HasChanges);
+        Assert.Single(diff.AttributeChanges);
+        Assert.Equal(DiffChangeType.Changed, diff.AttributeChanges[0].ChangeType);
+    }
+
     [Fact]
     public void ComputeDiff_AlarmDescriptionChange_DetectedAsChanged()
     {