fix: set Editable to Conditional and fix Visible xpath expression

patchConditionalSettings now sets the Editable BSON field to
"Conditional" when ConditionalEditabilitySettings is populated,
fixing mx check validation failure. Also restore $currentObject/
prefix in the Visible xpath example that was dropped during the
syntax refactor.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ako

mdl-examples/doctype-tests/03-page-examples.mdl

@@ -2277,7 +2277,7 @@ CREATE PAGE PgTest.P040_ConditionalProps
     ROW row1 {
       COLUMN col1 (DesktopWidth: 8, TabletWidth: 6, PhoneWidth: 12) {
         DATAVIEW dv1 (DataSource: MICROFLOW PgTest.DS_GetFirst) {
-          TEXTBOX txtName (Label: 'Name', Attribute: Name, Visible: [Name != empty])
+          TEXTBOX txtName (Label: 'Name', Attribute: Name, Visible: [$currentObject/Name != empty])
           TEXTBOX txtCountry (Label: 'Country', Attribute: Country, Editable: [true])
         }
       }

sdk/mpr/writer_widgets.go

@@ -123,6 +123,9 @@ func patchConditionalSettings(doc bson.D, w pages.Widget) bson.D {
 		if elem.Key == "ConditionalEditabilitySettings" && bw.ConditionalEditability != nil {
 			doc[i].Value = serializeConditionalEditability(bw.ConditionalEditability)
 		}
+		if elem.Key == "Editable" && bw.ConditionalEditability != nil {
+			doc[i].Value = "Conditional"
+		}
 	}
 	return doc
 }