Changes

tsk39: Refactors story exploration to integrate reusable pagination
logic
Replaces custom pagination with a shared `Paginated` class to centralize 
functionality. Updates `ExploreBean` and `Explore.xhtml` to streamline 
navigation, enhance maintainability, and correct typographical errors in
`availableGenres` and `availableThemes`. Creates method in service to 
count the number of filtered stories and adds tests to it.