[WIP] Add file reading and hash verification for branding

[Copilot]

Cloud agent has begun work on This file needs to r... and will update this pull request as work progresses.

Original prompt

This file needs to read the firest line from the file ../.branding download the tar.gz from that location compare its sha256 hash the the hash from the second line and then extract it into ../branding if the hashes match and print the hash mismatch otherwise. hash needs to be in a nix fetch compatible format.

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