Update PR via REST API

gh pr edit is broken due to GitHub deprecating Projects Classic (projectCards GraphQL field error). Use the REST API instead.

Rules

1. Never use gh pr edit to update PR title or body. It will fail with a GraphQL error.
2. Use gh api with the REST endpoint:

   gh api repos/{owner}/{repo}/pulls/{number} -X PATCH -f title="..." -f body="..." --jq '.html_url'
   

3. To get the current PR number and repo, use:

   gh pr view --json number,url,baseRefName
   

4. gh pr view and gh pr create still work fine. Only gh pr edit is affected.