Add GitHub Actions workflows for CI and CPAN release

CI workflow:
- Runs tests on push/PR across Perl 5.14 through 5.40
- Validates compatibility with the minimum supported version

Release workflow:
- Triggers on GitHub release publication
- Builds distribution tarball and uploads to CPAN
- Requires CPAN_USERNAME and CPAN_PASSWORD repository secrets

https://claude.ai/code/session_018RtsaLPCF2azHAQ1a6W7vk