Bold lines at body font size that are standalone (preceded by a paragraph
break) and have ≥3 words are promoted to headings. This catches the
common pattern in academic/technical PDFs where section headings use
bold text at the same size as body text.
Guards against false positives: minimum word count, colon-ending
exclusion (labels like "Table I:").
Benchmark improvement: MHS 0.37→0.50, overall 0.71→0.75.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
