- Add decode_page_content_streams() function for per-page lazy decode
- Update extract_page_from_dict() to support lazy stream decoding
- Modify extract_pdf() and extract_pdf_ndjson() to enable lazy decoding
- Fix borrow checker issue in LazyPageIter::next()
This ensures content streams are decoded lazily per page and dropped
immediately after processing, keeping peak RSS flat across page count.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
