Update GitHub PR Body

Important

Do NOT use gh pr edit --body - it fails with a GraphQL error about Projects (classic) deprecation. Always use the REST API approach below instead.

Instructions

When updating a GitHub PR body:

1. Get the current PR number (if not provided):

   gh pr list --head "$(git branch --show-current)" --json number --jq '.[0].number'
   

2. Get the current PR body to review existing content:

   gh pr view <pr-number> --json body -q '.body'