This dir holds all the files needed to build this app on all platforms. We store these files in the repo instead of downloading them at build-time because the tools used to download them do not provide secure authentication and integrity checks.
For more info, see:
There's a SHA256SUMS file in this directory that contains the sha256 hashes of the files in this directory.
You should also be able to use the download.sh script in this directory to re-download the assets.