enhanced audiobookshelf connection

[HoChiPants]

Purpose

This PR expands the AudiobookShelf browsing experience so users are no longer limited to a flat list of titles.

The main goal is to make the existing AudiobookShelf integration feel closer to the server's native browsing capabilities by adding support for browsing by Series, Collections, Authors, and Narrators, while preserving the existing book-list and detail flows.

This change also refactors the AudiobookShelf navigation and data flow so the same UI stack can handle:

• top-level AudiobookShelf libraries
• browse categories within a library
• filtered book lists
• collection contents
• existing audiobook detail views

Bugfix

Not a bugfix branch.

Related tasks

• Feature request: improve AudiobookShelf browsing beyond a flat title list
• Requested support for:
  • search
  • series
  • collections
  • authors
  • narrators

Approach

The general approach was to extend the current AudiobookShelf integration instead of creating a separate parallel flow.

Navigation and screen model

Added richer AudiobookShelf route/source modeling so a single library screen can represent multiple kinds of content:

• AudiobookShelfLibraryLevelData
• AudiobookShelfLibraryViewSource
• AudiobookShelfBrowseCategory
• AudiobookShelfItemFilter

This allows the same AudiobookShelfLibraryView / AudiobookShelfLibraryViewModel stack to render:

• library list
• browse-category list
• filtered books
• entity lists
• collection contents

Service/API updates

Extended AudiobookShelfConnectionService with support for additional AudiobookShelf endpoints and filtering behavior:

• fetchFilterData(in:)
• fetchCollections(in:)
• fetchCollection(id:)
• fetchItems(..., filter:)

The AudiobookShelf integration now uses:

• /api/libraries
• /api/libraries/{id}/filterdata
• /api/libraries/{id}/collections
• /api/collections/{id}
• /api/libraries/{id}/items?filter=...

UI updates

Updated the existing AudiobookShelf list/grid flows to support more than just books and libraries by expanding AudiobookShelfLibraryItem.Kind to include:

• browseCategory
• series
• collection
• author
• narrator

The existing row/grid views were reused and adjusted so these new item types can:

• display appropriate placeholder icons
• show subtitles where useful
• navigate correctly
• avoid enabling download-selection behavior for non-book entities

Search and browsing behavior

The existing search behavior for books remains in place.

New entity/category screens use local filtering where appropriate, while book-library screens continue to use the current AudiobookShelf search endpoint and filtered item fetches.

Things to be aware of / Things to focus on

• This PR is focused on AudiobookShelf audiobook libraries. Podcast-specific browsing was not expanded in the same way.
• The feature relies on AudiobookShelf server metadata being present in filterdata and collections responses. If a server/library has sparse metadata, some categories may naturally appear empty.
• The implementation intentionally reuses the existing AudiobookShelf screen stack rather than introducing a separate feature-specific UI flow.

Things to review:

• Navigation behavior between libraries, browse categories, filtered books, and details
• Correctness of AudiobookShelf filter encoding in AudiobookShelfItemFilter.queryValue
• Behavior of search, sorting, and pagination across the new screen sources
• Whether the current UX for single-library auto-navigation is desirable
• Whether collection and entity placeholder artwork behavior is acceptable for a first pass

Screenshots

[GianniCarlo]

Hi @HoChiPants ! thanks for the PR!, I've been looking into it and testing it, and I think we can improve on it by instead of having the intermediate screen with the navigation options, we do it with tabs for the different options, so it more closely resembles ABS navigation too, what do you think?

[HoChiPants]

Totally in. Check out the most recent change @GianniCarlo

[GianniCarlo]

My bad @HoChiPants , I should have been more specific, I meant tabs like in the toolbar at the bottom, like how the Files app shows up from within BookPlayer

current ABS	Files

[HoChiPants]

oohhhhh gotcha. Check out this push

[GianniCarlo]

@HoChiPants it was not quite there yet, the tabs were a custom view still, but I have the changes locally, I'll go ahead and merge this

[HoChiPants]

LETS GO! more than happy to do some more features if there is stuff you guys want.