Add the ability for the user to select multiple files and download them as one archive (flag `--sing #30
Description
Add the ability for the user to select multiple files and download them as one archive (flag --single-stream). We pack in zstd or tar.gz on the fly, no storage of files. When this is enabled we show checkboxes to the user. If a user selects one or more then below the table we show a link named archive.zstd and one archive.tar.gz - whichever they choose that's the file they download