Node.js Private Object Storage for User Documents: PDF, DOCX, and Expiring Access

High‑throughput receipt upload uses presigned browser writes to private object storage, requiring a real‑origin CORS preflight before direct uploads; otherwise receipts stream through a backend proxy. For media products that extract receipt data while retaining originals for audit, large‑file throughput is critical. Direct writes keep file bytes off the application server, but a backend proxy simplifies reasoning and deployment. Avatar‑sized images rarely make the bandwidth cost painful, whereas batches of high‑resolution scans do.