Support CNCF `.project` metadata format

the CNCF is rolling out a new metadata format:

https://contribute.cncf.io/blog/2026/04/22/introducing-dot-project-for-maintainers/

We may want to support this in CollectOSS, but also this is going to take a lot of planning to figure out how

Start by reading the linked CNCF announcement to understand the `.project` metadata format, then inspect CollectOSS's existing metadata collection and storage entry points. The issue does not identify files, tests, or an agreed implementation scope; done would first require a decided support plan and clear acceptance criteria.

Written by the indexing model from the issue text.