Fix incorrect struct tags for Page, TotalPages, and PageY fields.
Previously used 'int' tag instead of proper JSON field names,
which would cause serialization issues.
- Add internal/sync package with format detection
- FormatGroup types: reflowable, fixed_layout, comic_archive
- DetectFormatGroup() function based on mimetype and file extension
- MimeType mappings for common ebook formats
- Progress conversion engine with:
- ConvertProgress() between format groups
- Extract percentage from various progress formats
- PageToPercentage / PercentageToPage helpers
- CharacterToPercentage / PercentageToCharacter helpers
- MergeProgress() with 'max progress wins' strategy
- FormatProgressForDisplay() for UI rendering
- Add sqlc queries for format detection and progress updates
- BulkUpdateFormatGroups query for auto-format detection
- GetUniversalProgress query with all location references
- UpdateUniversalProgress query with device sync metadata
- ReadingHistory queries for session tracking
john-okeefe