[mtmail]

If I faced such a codebase (and I have just recently) then I'm interested in (a) installation instructions, pre-requisites, possibly data dumps (b) notes what a version 2 would look like, basically a brain-dump what you think could be improved or shortcomings. Honesty (engineer to engineer) works best. I never had to check the git history for debugging so a snapshot (or depth=1 export) would have been enough.

If you own all rights to the code base I think you can ask for attribution, e.g. "if you use this in a public facing projects you need to attribute <company name, url> on your about-us page." Kind of a one-sentence licence. Some people will ignore it. I would add a "version 1 written by <company> name" as a comment to the beginning of every file just to show where the code originated.