Implement advanced settings controls for ElevenLabs voices including Stability, Similarity Enhancement, and Style Exaggeration, similar to existing pitch/rate controls.

Acceptance Criteria

• Add Stability slider control (0.0 - 1.0) with descriptive labels
• Add Similarity Enhancement slider (0.0 - 1.0) with explanatory text
• Add Style Exaggeration slider (0.0 - 1.0) with usage guidance
• Settings should be per-voice and persist in user preferences
• Only show advanced settings for ElevenLabs voices
• Add real-time preview with sample text synthesis
• Include reset to defaults functionality
• Add tooltips explaining each setting's effect

Technical Implementation Notes

// Add to Speech.component.js after existing sliders
{
  voice?.voiceSource === "elevenlabs" && (
    <>
      <ListItem divider>
        <ListItemText
          primary="Stability"
          secondary="Controls voice consistency"
        />
        <Slider
          value={elevenLabsSettings.stability}
          onChange={handleStabilityChange}
          min={0}
          max={1}
          step={0.1}
          disabled={voice?.voiceSource !== "elevenlabs"}
        />
      </ListItem>
      {/* Similar for Similarity and Style */}
    </>
  );
}

Files to Modify

• src/components/Settings/Speech/Speech.component.js
• src/components/Settings/Speech/Speech.container.js
• src/providers/SpeechProvider/SpeechProvider.reducer.js