Changes

tsk43: 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.

tsk59: Implements story creation and update in service layer
This commit adds full support for creating and updating stories. It
introduces
`StoryCreateDto`, implements creation and update flows in
`StoryService`, and applies permission checks using the security role
caller for CREATOR actions. A new `UserService` is added to resolve the
current user. The `Story` entity now supports relaxed nullability for
drafts, immutability after publication, theme and text validations, and
a new `isComplete` method. The database schema is updated to match these
rules. The `StoryMapper` is adjusted for the updated entity constructor.
Comprehensive unit and integration tests verify creation, updating,
validation behavior, and authorization handling.

tsk39: Integrates advanced pagination and search improvements for
stories
Refactors `StoryManagedBean` to use a reusable `Paginated` class, 
centralizing pagination logic. Enhances `search.xhtml` with dynamic page 
size, navigation controls, and updated search result display. Updates
`StoryService` to add counts for published and filtered stories,
alongside improved query logic. Adds and updates related tests.