Add license and citation metadata for Zenodo and ORCID

[lpenap]

Summary

Groundwork for archiving releases on Zenodo and listing the project in ORCID.

• LICENSE: GNU GPL v3, same as java-monitor-example. Zenodo requires a license to publish an open-access record.
• CITATION.cff: title, abstract, author (Luis Augusto Peña Pereira, ORCID 0009-0001-0739-7149), repository, license, version 8, release date, keywords, and references to Gamma et al. and the companion project. GitHub renders it as "Cite this repository"; Zenodo reads it when archiving, and the ORCID iD lets DataCite link the record to the author's profile.
• README: license badge, a How to cite section with a commented-out Zenodo DOI badge to fill in after the first archive, and a License section. Table of contents updated.
• pom.xml: <url> and <licenses> declared.

After merging

1. Check that GitHub shows the "Cite this repository" button without a validation warning.
2. On zenodo.org, enable the repository under the GitHub tab.
3. Publish a new release (e.g. v8.1). Zenodo archives it and mints a version DOI plus a concept DOI.
4. Replace the placeholders in the README's How to cite section with the concept DOI.
5. In ORCID, authorise DataCite auto-update at commons.datacite.org, or add the DOI manually through Works → Search & link → DataCite.

Verification

• ./mvnw validate passes with the pom changes
• CITATION.cff parses as YAML; the ORCID iD resolves at pub.orcid.org and the name on record matches
• GitHub's own validator will flag any schema issue on the repository page

🤖 Generated with Claude Code