- Change audio files to not be stripped of metadata
- Automatically extract cover art from audio if it exists
- Add `thumbnail` parameter to `POST /api/v1/media`, `POST /api/v2/media` and `PUT /api/v1/media/:id`
- Add `icon` to represent it in attachments in ActivityPub
- Fix `preview_url` containing URL of missing missing image when there is no thumbnail instead of null
- Fix duration of audio not being displayed on public pages until the file is loaded

- Fix audio attachments not being represented in OpenGraph tags
- Fix audio being represented as "1 image" in OpenGraph descriptions
- Fix video metadata being overwritten by paperclip-av-transcoder
- Fix embedded player not using Mastodon's UI
- Fix audio/video progress bars not moving smoothly
- Fix audio/video buffered bars not displaying correctly

Fix #13403

Fix #9106