PR #729 tightened AdminAuth to require ADMIN_TOKEN, breaking the
workspace credential helper which called /admin/github-installation-token
with a workspace bearer token. Tokens expired after 60 min with no refresh.
Fix: Add /workspaces/:id/github-installation-token under WorkspaceAuth
so any authenticated workspace can refresh its GitHub token. Keep the
admin path as backward-compatible alias.
Update molecule-git-token-helper.sh to use the workspace-scoped path
when WORKSPACE_ID is set.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>