Audit GitHub metadata mapping quality

## Summary

Review the metadata imported from GitHub and identify fields that may be incomplete, inaccurate, or require user confirmation.

## Motivation

GitHub repository metadata is not always suitable for citation metadata without validation.

## Areas to Review

- Repository title
- Description / abstract
- Authors
- ORCID
- License
- Keywords
- Homepage
- Version
- Publication date

## Acceptance Criteria

- A list of known mapping limitations is documented
- Potential improvements are tracked as separate issues

Review the GitHub metadata import mapping and compare the listed fields with the citation metadata produced by OpenCite. Document each known limitation or validation concern, then create separate issues for potential improvements; the acceptance criteria define completion.

Written by the indexing model from the issue text.