GitHub App tokens expire after 1 hour — breaks long-running CI publishes

GitHub App installation tokens expire after 1 hour (non-configurable). For publish jobs exceeding this (e.g., sentry-native's ~1h 23m symbol upload), the token expires before Craft's post-publish git push for the release branch merge. Git fails with could not read Username for 'https://github.com': No such device or address — which looks like a credential config issue but is actually token expiration. No code change in Craft alone can fix this — the GITHUB_TOKEN env var, git http.extraheader, and Octokit all use the same expired token. The real fix requires the CI workflow (getsentry/publish) to generate a fresh token after the Docker container exits, before the merge step.