Renders a paginated grid of audiobook cards using the
useAudiobookLibrary hook. Each card links to /audiobooks/book/{id}.
Cards show poster, title, and year; falls back to a "No cover"
placeholder when the audiobook has no poster_url. Empty state hints
to operators that they need to set a library's type to 'audiobooks'.
Routes themselves are wired in Task 8 (navigation integration).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
