feat(rust): initialised cargo

nix/package.nix

@@ -0,0 +1,22 @@
+{
+  lib,
+  rustPlatform,
+  stdenvAdapters,
+  llvm,
+}: let
+  toml = (lib.importTOML ../Cargo.toml).package;
+  pname = toml.name;
+  inherit (toml) version;
+in
+  rustPlatform.buildRustPackage.override {stdenv = stdenvAdapters.useMoldLinker llvm.stdenv;} {
+    RUSTFLAGS = "-C link-arg=-fuse-ld=mold";
+
+    inherit pname version;
+
+    src = builtins.path {
+      name = "${pname}-${version}";
+      path = lib.sources.cleanSource ../.;
+    };
+
+    cargoLock.lockFile = ../Cargo.lock;
+  }