Promote every workspace project from `origin/local` to `origin/staging` in one pass — open a local→staging PR in each repo that has both branches, merge it after its checks pass, then watch the GitHub Actions runs on the merge commit and report success or failure per project. Use when the user says "promote local to staging", "open and merge local→staging PRs on all projects", or runs /local-to-staging. Never pushes, never touches a server, never bypasses branch protection, and never goes past staging — promotion to production is /staging-to-production. A broken staging deploy routes to /staging-fix.
