Scholarly identifiers: DOIs for patterns, ROR IDs for affiliations

[RichardLitt]

Follow-up from #144, which surfaces ORCID iDs for authors in the RSS feed. The catalogue itself still isn't formally citable in an academic sense. Splitting this out as its own issue.

• Mint a DOI for each pattern via Zenodo. GitHub has a native Zenodo integration: when the repo is released, Zenodo can mint a DOI for the whole release, or (with a bit more work) for each individual pattern file. Either makes the patterns formally citable in academic papers — a big win for the people who use these patterns in their grant applications and OSPO reports.
• Add ROR IDs to author affiliations in authors.yml, alongside the existing free-text affiliation strings. ROR is the open standard for institutional identifiers — same idea as ORCID for people, but for universities and labs.
• Surface DOIs and ROR IDs in the RSS feed metadata so that scholarly graph crawlers (OpenAlex, Crossref, OpenAIRE) can ingest the catalogue and link patterns to their authors and institutions.

The end-state is that a researcher reading a CURIOSS pattern can cite it like any other scholarly output, and that scholarly indexing services can find and surface our patterns the same way they find papers.