set up license

[kaze-cow]

Description

Add the LGPL 3.0, MIT, and Apache 2.0 licenses to the repo, and link the relevant disclosures and package attribution where necessary.

How to test

Verify that the license text is correct.

Verify that we have followed the relevant steps for our repo as documented by GNU (excluding the individual source file warnings, as im leaving that as out of scope for now since its a bigger project/decision) https://www.gnu.org/licenses/gpl-howto.en.html, and we are following standard patterns for the other two licenses.

Verify that the license is properly linked in our project workspace and packages.

Verify the readme notice is OK.

[fedgiac]

Looks good!
I didn't know about the COPYING files, but looks good.
Despite the link, I'm still not sure whether we're supposed to update the copyright notice in the GPL licenses themselves. 🙈
But I suppose not because that's the copyright of the license file itself?

How I checked the license files

No important diffs found with other versions of these files found online:

~$ diff <(curl --silent 'https://www.gnu.org/licenses/gpl-3.0.txt') <(curl --silent 'https://raw.githubusercontent.com/cowprotocol/solana-programs/license/COPYING.GPL')
674a675
> 
~$ diff <(curl --silent 'https://www.gnu.org/licenses/lgpl-3.0.txt') <(curl --silent 'https://raw.githubusercontent.com/cowprotocol/solana-programs/license/COPYING.LESSER')
~$ diff <(curl --silent 'https://www.apache.org/licenses/LICENSE-2.0.txt') <(curl --silent 'https://raw.githubusercontent.com/cowprotocol/solana-programs/license/COPYING.APACHE')
1d0
< 
$ diff <(curl --silent 'https://raw.githubusercontent.com/WisTex/The-MIT-License-Files/refs/heads/main/LICENSE') <(curl --silent 'https://raw.githubusercontent.com/cowprotocol/solana-programs/license/COPYING.MIT')
3c3
< Copyright (c) 2022 WisTex TechSero Ltd. Co.
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> Copyright (c) 2026 CoW Foundation