Two bugs in collect_text_in_region / extract_text_in_regions_mem:
1. The threshold-based sort comparator in collect_text_in_region was not
transitive, causing Rust's sort to panic on certain PDFs. Replaced with
strict total_cmp ordering — the line-grouping phase already handles
fuzzy Y matching via threshold.
2. The needs_ocr check was missing is_cid_garbage, so Identity-H fonts
with CID garbage (C1 control chars, high Latin mojibake) could pass
all quality checks and be served as real text with needs_ocr=false.
Also adds 7 integration tests for extract_text_in_regions_mem (previously
had zero coverage): basic extraction, Identity-H needs_ocr, multiple
regions, nonexistent page, empty region, invalid input, and a fast-vs-normal
comparison test across all text-based fixtures.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
