Add @OverRide annotation to toMap method in Dart models

Added @OverRide annotation to the toMap() method in model template to properly indicate that it overrides the Model interface method, resolving the annotate_overrides lint warning.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ChiragAgg5k

templates/dart/lib/src/models/model.dart.twig

@@ -59,6 +59,7 @@ class {{ definition.name | caseUcfirst | overrideIdentifier }} implements Model
         );
     }
 
+    @override
     Map<String, dynamic> toMap() {
         return {
 {% for property in definition.properties %}