DEPRECATED — Firmware is now stored in MinIO (S3-compatible object store).

Old approach: Static .bin files served by Nginx ota-server.
New approach: Upload via POST /release to ota-release service.
  → Stored in MinIO with versioning
  → 48h pre-signed download URLs generated automatically
  → fwlatest manifest pushed to ThingsBoard shared attributes

This directory is no longer mounted by any container.