entrypoint.sh now requires RUN_SEED=true to execute the seed script.
Without it, only 'flask db upgrade heads' runs on container start.
docker-compose.yml (dev) sets RUN_SEED=true and RUN_CSV_IMPORT=true
so local development behaviour is unchanged.
Production (docker-compose.prod.yml) does not set these variables,
so the database is no longer wiped on every deploy.
