Adds vcs.go with:
- vcsClient interface that main.go uses for all VCS operations
- githubAdapter that wraps *github.Client and converts types to gitea types
- newVCSClient() factory: detects VCS type via GITHUB_API_URL env var
(set by GitHub Actions runners; absent on Gitea) and returns the
appropriate client
- buildRepoPersonaClient() adapter for LoadRepoPersonas
- detectVCSType() and githubAPIBaseURL() helpers
Detection logic mirrors action.yml: GITHUB_API_URL present → github,
absent → gitea. On GitHub/GHES, uses GITHUB_API_URL as the API base URL
(trusted platform value), never user-supplied vcsURL.
Rodin
1e1a50581f