There are some command line tools to do this (see other comments), and I think they use ffmpeg under the hood.

They work, and I built a version of one myself as a proof of concept before I started this, but I quickly realized I wanted visual feedback and ability to preview the edits before exporting. Without that it’s a lot of guess-and-check.

With Recut I can tweak the padding value, hit play, see if it sounds right, and only export once.