CI format check was failing because the pinned toolchain
rust-toolchain.toml overrides the `dtolnay/rust-toolchain@stable +
rustfmt` action installation — rustup installs rustfmt onto the
stable channel, but when cargo fmt runs inside the repo, rustup
honors the 1.94.1 pin and does an on-demand install that pulls only
rustc/cargo/rust-std.
Declaring components in rust-toolchain.toml ensures the on-demand
install of the pinned toolchain includes rustfmt.
Pin Rust toolchain to 1.94.0 via rust-toolchain.toml for deterministic
compiler output across environments. Set SOURCE_DATE_EPOCH from git
commit timestamp in CI workflows and packaging scripts to normalize
embedded timestamps.
Make packaging archives reproducible: pass --mtime=@$SOURCE_DATE_EPOCH
to tar in .deb, .ipk, and systemd tarball builds. Normalize ownership
to root:root in systemd tarballs. Pin cargo-zigbuild to 0.19.8 for
cross-compilation stability.
Add SHA-256 hash output to CI build and OpenWrt packaging workflows
for binary verification.
