feat: add bulk deployment script for gh-aw auto-upgrade workflow

- Deploys gh-aw-auto-upgrade.yml to all repos in an org via GitHub API
- Auto-detects branch protection, falls back to PR creation + merge
- Filters to repos with gh-aw .md workflows, skips archived repos
- Idempotent: SHA-compares before writing, skips identical files
- Flags: --org, --token, --dry-run, --repos (subset targeting)

Author: zircote