Adds scripts/generate-qr.ts that generates one 400px PNG per warehouse
zone into public/qr/ (gitignored). Encodes /report?zone=<token> URL per
zone using NEXT_PUBLIC_APP_URL (default http://localhost:3000). Adds
public/qr/.gitkeep so the output directory is tracked. All 8 tests pass.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AWxyMibCuGGtSQSqfajDQ7
