Implement HOCR XML parser for Tesseract output (Phase 5.4.3).
- Add quick-xml dependency for streaming HOCR parsing
- Implement HocrWord struct with text, bbox_px, confidence_0_100 fields
- Implement parse_hocr() using quick-xml event-driven parsing
- Handle invalid UTF-8 gracefully (U+FFFD substitution)
- Skip empty/whitespace-only words
- Parse title attribute robustly (tolerates extra fields)
- Default confidence to 50% when x_wconf missing
- Add comprehensive test suite with performance benchmark
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
