Audit of all external contributor PRs revealed 97 commit emails
not mapped in AUTHOR_MAP, meaning contributors weren't properly
credited in release notes. Cross-referenced via:
- GitHub API email search (9 resolved before rate limit)
- Salvage PR body mentions (@username in descriptions)
- Git noreply email cross-reference (same person, both emails)
- GH contributor list username matching
Also adds .mailmap for git shortlog/log display consistency.
Remaining 22 unmapped emails need GH API resolution when rate
limit resets — the contributor_audit.py script will flag them.
Addresses ColourfulWhite's report about missing contributor tags.
