chore: atualiza refs de master->main e GitHub->GitLab

- changelog.js (3 apps): link "Compare commits" agora aponta para
  GitLab (/-/commits/main) com rótulo gitlab.ufpe.br.
- generate-build-info.js (3 apps): fallback de branch master -> main.

Acompanha a migração da branch principal master -> main no GitLab.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>