Implements the SpeechSettings component with four sections:
- STT settings (enable/disable, language preference)
- TTS settings (enable/disable, voice selector, tier preference, auto-play, speed control)
- Voice preview with test button
- Provider status with health indicators
Also adds Slider UI component and getHealthStatus API client function.
30 unit tests covering all sections, toggles, voice loading, and PDA-friendly design.
Fixes#404
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>