Keep the native APK indexes alongside the expanded package
metadata so image builds do not fetch mutable repository state.
Generate pins atomically and retry transient generation failures.
Pinned OpenWrt feed hashes for realtek/rtl930x on snapshot and 25.12.5,
generated with nix-openwrt-imagebuilder's release2nix.
Expanding the feeds locally (rather than relying on upstream's index-level
hashes) keeps every package a plain pinned fetchurl, and removes the
import-from-derivation that would otherwise make evaluation depend on the
OpenWrt download server.
jackos1998