Fix Listen highlighting speed and translation display

[Talljack]

Summary

• Keep Listen/Read fallback sentence highlighting aligned with cloud audio by starting estimated timers only after audio playback begins
• Scale Edge TTS word timestamps to the selected playback speed so 0.5x highlighting does not outrun the audio
• Render fetched Listen translations instead of only rendering translation errors

Verification

• pnpm typecheck
• pnpm lint
• pnpm test
• Browser smoke: http://localhost:3001/listen/codex-listen-speed-translation showed Listen content at 0.5x with Chinese translation visible

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
echo-type	Ready	Preview, Comment	May 25, 2026 2:00pm