fix: Prefix class names with Pagy module to prevent collisions

[LuukvH]

This commit updates the code to prefix certain class names with the Pagy module name. The change is necessary to prevent potential collisions with class names defined in Rails applications.

These adjustments ensure that the Pagy pagination library operates correctly without interfering with other classes that might exist within the application namespace. The revised code now properly isolates Pagy-specific classes, enhancing compatibility and stability