Add a flake that builds all four binaries (fips, fipsctl, fips-gateway,
fipstop) on Linux and macOS, pinning the exact toolchain from
rust-toolchain.toml (1.94.1 + rustfmt/clippy) via fenix so Nix builds
match CI and the AUR/Debian packaging.
Wire up the build-time native deps the source tree needs: pkg-config and
bindgenHook (libclang) for the rustables/libdbus-sys bindgen step, and
dbus for bluer's BLE support. autoPatchelfHook rewrites the binary RPATHs
so the daemon resolves libdbus-1.so.3 and libgcc_s.so.1 from the Nix store
at runtime — without it `fips` fails to load on NixOS, which has no global
/usr/lib.
Outputs: packages.{default,fips}, apps for each binary, checks.fips, and a
devShell with the pinned toolchain plus cargo-edit. Tests are skipped in
the package build since they exercise TUN devices, raw sockets, and mDNS
that aren't available in the sandbox, mirroring the AUR/Debian packaging.
Verified end-to-end in a pure Nix store (nixos/nix container): nix build,
nix flake check, and running all four binaries succeed against the
committed flake.lock.
Documented across the install and developer docs: a Nix / NixOS section in
packaging/README.md, the from-source guide in docs/getting-started.md
(noting the flake produces binaries only, with NixOS system integration
through the system configuration rather than the installer), the CHANGELOG,
README, CONTRIBUTING, and the v0.4.0 release notes.
Co-authored-by: Johnathan Corgan <johnathan@corganlabs.com>