Adds full support for book lists managed by the Companion App:
- New /list API endpoints (GET/POST) for uploading, retrieving, and deleting lists
- BookListStore for binary serialization of lists to /.lists/ directory
- ListViewActivity for viewing list contents with book thumbnails
- Reading Lists tab in My Library with pin/unpin and delete actions
- Pinnable list shortcut on home screen (split button layout)
- Automatic cleanup of pinned status when lists are deleted
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