Implement per-word validation filter for assisted-OCR BrokenVector path.
Changes:
- Add SpanSource::OcrAssisted variant to hybrid.rs
- Add Span::ocr_assisted() helper method
- Implement validate_ocr_with_position_hints() in ocr.rs
- 5pt distance threshold for position validation
- 0.4 confidence cap for rejected words
- Linear scan for nearest-neighbor lookup
- Add unit tests for validation filter
Closes: pdftract-3s2i
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
- Fix extract_page_inner typo: changed to extract_page (function was undefined)
- Add error_count field to ExtractionMetadata struct
- Add error field to PageResult struct (missing in constructor)
- Add semaphore module to lib.rs exports
The parallelism capping implementation was already in place but had bugs
preventing compilation. This fixes those bugs so the semaphore-based
bounding of in-flight pages works correctly.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
