fix: allow direct postgres in production

[maotora]

Summary

• allow production to run with a direct PostgreSQL DATABASE_URL instead of requiring Prisma Accelerate
• update README guidance so production can use either direct Postgres or Accelerate

Testing

• pnpm build
• pre-commit hook (pnpm lint && pnpm typecheck)

Notes

• local pre-push DB checks require a direct PostgreSQL URL in this shell and were not runnable here