- remove MONGODB_URI from .env.example (Atlas migration done; deleted from
Vercel cloud env too)
- trim .env.deploy.example to vars actually consumed by deploy scripts
(Upstash creds were only needed by the now-deleted migration script)
- README config table: drop ENV / SOURCE_COMMIT / SCHEDULE_CHECK_APP_TIME
(never read by code; Java-era leftovers)
- check-secret-leaks: drop MONGODB_URI; add UPSTASH/KV/CRON tokens; widen
scan roots to include api/
- add scripts/list-upstash-keys.js read-only ops helper
