- Change `by_popularity` method in `City` model to use `start_time` for filtering views.
- Update `by_popularity` in `WeatherArt` model to limit results and incorporate the correct popularity calculation.
- Adjust `HomeController` to define `@popular_shuffle_arts` and `@latest_arts` with appropriate scopes.
These changes improve the accuracy of popularity retrieval for both cities and weather arts, simplifying the logic in the controller and leveraging updated model methods for performance.