Contributor terms: name the licence per location and add a patent grant for MIT contributions

Part of the licence rule (decision issue filed alongside). `CLA.md` describes one licence for everything and leans on MPL-2.0 for patents.

## Change

- Say which licence a contribution ships under: MPL-2.0 for files in the core, MIT for modules and everything else. Clause 2 already allows both.
- **Add an explicit patent licence.** Clause 4 points at MPL-2.0 section 2.1(b); MIT carries no patent grant, so contributions to MIT packages would otherwise carry none. A short grant in the terms themselves covers both.
- Keep the promise that the project cannot release a contribution as closed source.
- Use the same text, adjusted per repository, in barakoBrew, barakoPress and BaryoVM (tracked in each repository).

## Done when

- `CLA.md` names the licence per location, contains its own patent grant, and a reader can tell from it alone what their contribution ships under.

Plan page: https://claude.ai/code/artifact/09aef3dd-936d-432a-8056-9ef9bccfe8df

Start with CLA.md and compare its current licence and patent language with the issue's requested per-location terms. Update the document so core files use MPL-2.0, modules and other files use MIT, include an explicit patent grant, and preserve the no-closed-source promise. Done when the contribution licence is clear from CLA.md alone and the corresponding repository versions are aligned.

Written by the indexing model from the issue text.