Audiobook USB preparation

- Connect Audiobookshelf and browse your library.
- Preview chapter MP3s; divide long chapters into equal parts under 20 minutes.
- Continuous filenames and track numbers; book/author/narrator metadata and cover artwork.
- 128 kbps CBR, 44.1 kHz stereo MP3 with ID3v2.3.
- Sequential, flushed, verified USB copying without overwriting existing book folders.
- Tempo Web Prepare for USB opens the selected book using the podcastusb protocol.
- Run the updated desktop app once to register the shortcut.
