feat: add nix flake

Author: pilz0

.gitignore

@@ -0,0 +1 @@
+result

flake.lock

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+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }: {
+    overlays.default = final: prev: {
+      proserver-cli = final.callPackage
+        ({ stdenv, pkgs, ... }:
+          stdenv.mkDerivation {
+            src = ./.;
+            pname = "proserver-cli";
+            version = "1.0.1";
+          }
+        )
+        { };
+    };
+  } //
+  (flake-utils.lib.eachDefaultSystem (system:
+    let
+      pkgs = import nixpkgs {
+        system = system;
+        overlays = [ self.overlays.default ];
+      };
+      lib = nixpkgs.lib;
+    in
+    {
+      packages = {
+        proserver-cli = pkgs.writeScriptBin "proserver-cli" (builtins.readFile ./proserver);
+        default = self.packages.${system}.proserver-cli;
+      };
+      formatter = pkgs.nixpkgs-fmt;
+
+    }
+  ));
+}