feat: make a simple nix devshell, integrated with direnv

Author: teesh3rt

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1 +1,2 @@
 target
+.direnv

flake.lock

@@ -0,0 +1,13 @@
+{
+  description = "rebox: remaking busybox with rust";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    import-tree.url = "github:vic/import-tree";
+  };
+
+  outputs = inputs:
+    inputs.flake-parts.lib.mkFlake {inherit inputs;}
+    (inputs.import-tree ./packages/nix);
+}

flake.nix

@@ -0,0 +1,7 @@
+{...}: {
+  perSystem = {pkgs, ...}: {
+    devShells.default = pkgs.mkShell {
+      packages = [pkgs.cargo];
+    };
+  };
+}

packages/nix/shell.nix

@@ -0,0 +1,5 @@
+{...}: {
+  systems = [
+    "x86_64-linux"
+  ];
+}