chore: update test mode to prioritize data-testid

Author: elianiva

.roomodes

@@ -58,6 +58,7 @@ customModes:
       - Add JSDoc comments for complex test scenarios
       - Ensure mocks are properly typed
       - Verify both positive and negative test cases
+      - Prioritize using data-testid attributes for querying elements in the DOM
   - slug: design-engineer
     name: 🎨 Design Engineer
     roleDefinition: >-