removed nix artifacts

nix/devshell/flake-module.nix

@@ -1,25 +0,0 @@
-{ inputs, lib, ... }: {
-  imports = [
-    inputs.devshell.flakeModule
-  ];
-
-  config.perSystem =
-    { pkgs
-    , ...
-    }: {
-      config.devshells.default = {
-        imports = [
-          "${inputs.devshell}/extra/language/c.nix"
-          # "${inputs.devshell}/extra/language/rust.nix"
-        ];
-
-        commands = with pkgs; [
-          { package = rust-toolchain; category = "rust"; }
-        ];
-
-        language.c = {
-          libraries = lib.optional pkgs.stdenv.isDarwin pkgs.libiconv;
-        };
-      };
-    };
-}

nix/rust-overlay/flake-module.nix

@@ -1,18 +0,0 @@
-{ inputs, ... }:
-let
-  overlays = [
-    (import inputs.rust-overlay)
-    (self: super: assert !(super ? rust-toolchain); rec {
-      rust-toolchain = super.rust-bin.fromRustupToolchainFile ../../rust-toolchain.toml;
-
-      # buildRustCrate/crate2nix depend on this.
-      rustc = rust-toolchain;
-      cargo = rust-toolchain;
-    })
-  ];
-in
-{
-  perSystem = { system, ... }: {
-    _module.args.pkgs = import inputs.nixpkgs { inherit system overlays; config = { }; };
-  };
-}