Refactors book cover and metadata handling out of Epub class into a dedicated BookCoverUtils utility. Moves FootnoteEntry struct into reader activity directory. Simplifies cache clearing to use direct storage operations instead of Epub class.
Implements bidirectional conversion between KOReader XPath positions and FreeInkBook character offsets. Uses streaming SAX parsing to match chapter text accounting with ChapterLayout, enabling position sync without requiring DOM or pagination. Handles element ancestry tracking, text offset calculation, and spine index extraction.