Extract KokoroTtsProvider from factory into its own module with:
- Full voice catalog of 54 built-in voices across 8 languages
- Voice metadata parsing from ID prefix (language, gender, accent)
- Exported constants for supported formats and speed range
- Comprehensive unit tests (48 tests)
- Fix lint/type errors in chatterbox provider (Prettier + unsafe cast)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
