Use git ls-remote for autoloop branch discovery

[Copilot]

git branch -r --list origin/autoloop/* requires remote-tracking refs to be present locally, which they aren't in shallow checkouts (the default for actions/checkout). This causes the sync-branches workflow to silently find no branches.

Switch to git ls-remote --heads origin autoloop/* which queries the remote directly.

• workflows/sync-branches.md — Replace git branch -r with git ls-remote --heads and update parsing for the <sha>\trefs/heads/<branch> output format
• .github/workflows/sync-branches.lock.yml — Same change in the compiled Python version

// BeforeconstlistResult=git('branch','-r','--list','origin/autoloop/*');// ....map(b=>b.replace('origin/',''));// AfterconstlistResult=git('ls-remote','--heads','origin','autoloop/*');// ....map(b=>b.replace(/^.*refs\/heads\//,''));