Expand ability to support adaptors for other repository platforms

This was one of the pieces from feedback on the BOSC submission. Right now we're only pulling content from HF (models, datasets) and GitHub (code). But there are known reservations about GitHub (and HF), and there other possibilities, for example (in likely descending order of priority):

- [Gitlab](https://gitlab.com)
- [Codeberg](https://codeberg.org/explore/repos)
- Dryad (I don't think there's an "organization" equivalent?)
- Zenodo (could use a dedicated collection as the "organization" equivalent?)
- Preprint servers? (this would introduce another product type "paper"?)

It seems that previously existing model zoos have mostly transitioned to HF?

Start by tracing the existing GitHub and Hugging Face content integrations in the repository and identify how repository-platform adapters are represented. The issue does not name files, tests, or acceptance criteria; before implementation, define which platforms and product types are in scope and how completion will be verified.

Written by the indexing model from the issue text.