NIGHTLY_BASE_URL

Base URL for the nightly firmware channel. Absolute, and not routed through API_BASE_URL — the nightly build is published outside the API, flat at this host's root: index.json alongside every per-target artifact.

The version pointer and the artifacts must both be read from this host. Nightly and RELEASE_BASE_URL are separate buckets tracking different firmware commits, so a version taken from one resolves artifact filenames that do not exist on the other.