Merge Stacked PRs

Merge a linear chain of stacked PRs into main one at a time, re-targeting each subsequent PR to main before merging.

Workflow

1. Discover the stack

gh pr list --state open \
  --json number,title,headRefName,baseRefName,additions,deletions \
  --jq '.[] | "#\(.number) \(.headRefName) → \(.baseRefName) (+\(.additions) -\(.deletions))"'

If a branch prefix argument is provided, filter to only PRs whose branch names match it. Confirm the PRs form a single linear chain ending at main. Show the user the full stack, bottom to top, and get confirmation before proceeding.