Add Academy-rules-based nikkud→ktiv male converter (91.6% accuracy
vs 77.2% for strip_nikkud) and v0.20 adaptive sentence difficulty
cloze design spec. The converter enables frequency-based sentence
scoring by properly resolving nikkud tokens to their ktiv male forms
for frequency corpus lookup.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
