Add unit test verifying that U+00B7 middle dot is not stripped from Catalan
words during audio text preprocessing, reflecting multilingual requirements.
Move canonical audio text preprocessing logic to new shared module `audio-text.ts`
to ensure consistent normalization across worker, client, and NLP code. Update
all consumers to import and use the shared rules, eliminating duplication and
preventing drift. Expand glyph stripping to handle additional decorative
characters. Add unit tests for new cases and update documentation accordingly.