Add env: GITHUB_TOKEN to the Linux workflow step, then read it in
ci/main.go and inject it into each test container via WithSecretVariable
(for both GITHUB_TOKEN and GH_TOKEN). This prevents 403 rate-limit
errors on GitHub API calls (neovim/nvm releases) and authenticates
gh CLI for gh extension install inside the containers.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Unauthenticated GitHub API calls share the runner IP (60 req/hour limit).
net.go already uses GITHUB_TOKEN as a Bearer token when present.
gh CLI also needs GH_TOKEN to authenticate for gh extension install.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>