CODECHECK-related metadata are exported to CrossRef / DataCite

Exploring the inclusion of check-related metadata in scholarly metadata exports and deposits via **existing** export plugins - are there any hooks at all?

This is a complex task because likely there are not readily usable fields for the information, and it might not be easy to just add links between resources in the exports, because the certificates are not yet part of a public open database/academic graph.
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## Related User Stories

- C-AD1 (related): As a codechecker, I want the plugin to automatically reserve a certificate identifier, create the Register issue...
- R-SC3 (related): As a reader, I want the article's landing page to provide structured, direct links to the verified code repository...
- P-SD1 (related): As a publisher, I want the CODECHECK process to follow the same metadata schema, validation rules...
- P-SD2 (related): As a publisher, I want CODECHECK metadata to be included in my journal's Crossref and DataCite deposits...
- P-SD3 (related): As a publisher, I want the plugin to reserve certificate identifiers, create and update Register issues...

_User story references from the [CHECK-PUB User Stories document](https://codecheck.org.uk/pub/)._