Add support for hiding audiobooks that are already available by introducing a hideAvailable query flag and excluding matching ASINs at the DB level. Implemented getAvailableAsins() in audiobook-matcher to gather ASINs from the library and completed requests, and wired it into the popular and new-releases API routes to apply a notIn filter. Propagated the hideAvailable flag through useAudiobooks so client requests include the parameter, and adjusted the homepage to reset pagination when the flag changes. Replaced two StickyPagination instances with a new UnifiedPagination component (new file) that provides a single context-aware floating paginator which tracks the dominant section and allows switching between Popular and New Releases. Also removed client-side filtering in favor of server-side exclusion and made small imports/cleanup in page.tsx.
Introduces 'series' and 'seriesPart' fields to the Audiobook model and database schema. Updates API routes, file organization, and path template utilities to support series metadata. Enhances chapter merging logic, improves notification backend testing, and expands test coverage for admin and API routes.