Review a Pull Request

Review PR $ARGUMENTS and produce a confidence score for merge readiness.

Phase 1: Gather PR Context

# PR metadata
gh pr view $ARGUMENTS --json title,body,author,labels,files,additions,deletions,baseRefName,headRefName,state,isDraft,number

# Changed files list
gh pr diff $ARGUMENTS --name-only

# Full diff
gh pr diff $ARGUMENTS

# CI status
gh pr checks $ARGUMENTS