Download GitHub PR user-attachments images with gh token via curl

Screenshots embedded in PR bodies as https://github.com/user-attachments/assets/<uuid> can't be fetched by gh api or anonymous fetch tools, and on private or org repos they often return 404 without auth. curl -sL -H "Authorization: token $(gh auth token)" -o shot.png <url> follows the redirect to the signed S3 URL and returns the real PNG. Check the result with file shot.png before reading it as an image. Related zsh gotcha: a bare echo === in a zsh command fails with '== not found' (equals expansion), so quote separators like echo '==='.