integrate noise cleanup filter

Due to issues with the recording setup, the dc24 recordings from 2024-07-28 have very bad audio.

@philh found a tool that looks like it is able to clean up the audio somewhat: https://github.com/Rikorose/DeepFilterNet

This issue is meant to document that this is the tool that we used.

Maybe an audio cleanup step could be added somewhere in the cutting flow.

Note that it should not be the default, as the filter seems to remove applause. Maybe a checkbox in the audio part of the preview page.