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.

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/DiffService.cs

@@ -119,6 +119,11 @@ public class DiffService
         a.CanonicalName == b.CanonicalName &&
         a.Value == b.Value &&
         a.DataType == b.DataType &&
+        // #290: ElementDataType is part of the revision hash, so the diff must
+        // treat a List element-type change (e.g. Int32 → Double) with identical
+        // JSON-encoded values as a Changed attribute — keeping the structured
+        // diff in parity with the staleness hash.
+        a.ElementDataType == b.ElementDataType &&
         a.Description == b.Description &&
         a.IsLocked == b.IsLocked &&
         a.DataSourceReference == b.DataSourceReference &&

src/ZB.MOM.WW.ScadaBridge.TemplateEngine/Flattening/RevisionHashService.cs

@@ -53,6 +53,7 @@ public class RevisionHashService
                     CanonicalName = a.CanonicalName,
                     Value = a.Value,
                     DataType = a.DataType,
+                    ElementDataType = a.ElementDataType,
                     Description = a.Description,
                     IsLocked = a.IsLocked,
                     DataSourceReference = a.DataSourceReference,
@@ -174,6 +175,16 @@ public class RevisionHashService
         /// </summary>
         public string? Description { get; init; }
         /// <summary>
+        /// For List attributes: the element scalar type name; null otherwise.
+        /// Folded into the hash (#290) so a List element-type change (e.g.
+        /// Int32 → Double) with identical JSON-encoded values is detected as a
+        /// staleness/revision change. Null for scalar attributes — and because
+        /// the serializer ignores null properties
+        /// (<see cref="JsonIgnoreCondition.WhenWritingNull"/>), scalar-only
+        /// configurations hash identically to before this field was added.
+        /// </summary>
+        public string? ElementDataType { get; init; }
+        /// <summary>
         /// Whether the attribute is locked.
         /// </summary>
         public bool IsLocked { get; init; }