Add a "Resolving Conflicts in GitHub PRs" section to AGENTS.md with
step-by-step instructions for force-fetching refs, rebasing, resolving
lockfile conflicts, and verifying mergeability.
Add shell/resolve-pr-conflicts.sh that automates the workflow: fetches
metadata, force-updates the base ref, rebases, auto-resolves lockfile
conflicts via pnpm install, force-pushes, and verifies the result.
