OpenWrt Rust feed with guaranteed CI LLVM artifacts

How to use?

After ./scripts/feeds install -a, replace the default Rust package:

rm -rf feeds/packages/lang/rust
git clone https://github.com/sbwml/packages_lang_rust feeds/packages/lang/rust

This feed maintains Rust’s CI‑generated LLVM artifacts in a persistent and always‑available state.
It ensures llvm.download-ci-llvm = true works reliably across Rust versions, avoiding the common 404/cleanup issues from upstream CI and providing a consistent bootstrap environment for OpenWrt builds.