## Summary
- **What is the goal of this PR?** Add chapter selection support to the
XTC reader activity, including parsing chapter metadata from XTC files.
- **What changes are included?** Implemented XTC chapter parsing and
exposure in the XTC library, added a chapter selection activity for XTC,
integrated it into XtcReaderActivity, and normalized chapter page
indices by shifting them to 0-based.
## Additional Context
- The reader uses 0-based page indexing (first page = 0), but the XTC
chapter table appears to be 1-based (first page = 1), so chapter
start/end pages are shifted down by 1 during parsing.
