fix: only auto-convert bare attribute names to toString()

The toString() auto-conversion should only apply to bare attribute
names in DataView context (e.g., "TotalOrders"), not to $param.Attr
references (e.g., "$order.OrderDate") which are resolved via
SourceVariable/AttributeRef and handled correctly by Mendix.

Converting $param.Attr patterns produced invalid expressions like
toString($currentObject/$order.OrderDate) causing CE0117 errors.

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

Author: ako

mdl/executor/cmd_pages_builder_v3.go

@@ -1188,8 +1188,10 @@ func (pb *pageBuilder) resolveTemplateAttributePathFull(attrRef string, param *p
 
 	// For other patterns, resolve and check type
 	resolved := pb.resolveTemplateAttributePath(attrRef)
-	if pb.isNonStringAttribute(resolved) {
-		// Convert to toString() expression for non-String attributes
+	if !strings.HasPrefix(attrRef, "$") && pb.isNonStringAttribute(resolved) {
+		// Convert bare attribute names to toString() for non-String types.
+		// Only for bare names (e.g., "TotalOrders") in DataView context,
+		// not for $param.Attr references which are resolved via SourceVariable.
 		param.Expression = "toString($currentObject/" + attrRef + ")"
 		return
 	}