LanguageForms gains an optional Pronunciation: bare stress-marked IPA, ruled_by,
date, source and a rejected list. The store checks its shape and freezes a
ruling once set. pronounce() and `weksa lower --ipa` print the stored IPA of each
cited entity and refuse with NoPronunciation / NoEntityReferent; rejected
variants are never read. Nibu is the first entry: ˈnibu, rejected ˈnɪbu.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>