Must be built using a git| URL as they vendor their own libraries with git submodules.

@Icosahunter: Always happy to see a new contributor! ?

So, this package request has already been accepted, and then simply frozen due to lack of activity. Since you want to submit a patch and maintain this package, I'll simply re-open the task.

Now, since you say you already have a package build working, I assume you are familiar with part of our packaging documentation at least. Did you follow the steps in "Building a Package"? If so, perfect! The next steps are described in "Submitting the Package". Make sure to call your patch something like "Initial inclusion of SolveSpace", and mention "Resolves T5574" in the summary, so it connects to this request here.
After you've submitted your patch people from the team will start the review (as soon as someone has time for it). Most likely there will be a couple issues to iron out, so you'll have to update your patch according to the reviewer's request. But we'll see about that when we get to it.