API stats frozen — crawler stopped since ~May 27

## Bug Description

The production API at moltgraph-production.up.railway.app is returning stale statistics since ~May 27.

## Evidence
/api/stats returns identical values for 4+ days. All high=0, crawl stuck at 64.

## Environment
- API: https://moltgraph-production.up.railway.app
- Endpoint: /api/stats
- First observed: ~2026-05-27
- Still frozen: 2026-05-31