fix AF-2609
webm container with opus has limited support on Safari. Change to mp4 instead.
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## Summary by CodeRabbit
- **New Features**
- Audio recordings are now saved in MP4 format instead of WebM, improving compatibility with a wider range of devices and applications.
- **Chores**
- Updated dependencies to use MP4 muxing tools in place of WebM.
- Internal audio encoding utilities and references updated to support MP4 container format.
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