🧱 Add Nix flakes for building locally

flake.nix

@@ -0,0 +1,40 @@
+{
+  description = "Jekyll website template";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        formatter = pkgs.nixpkgs-fmt;
+        devShells.default = pkgs.mkShell {
+          buildInputs = [
+            pkgs.ruby
+            pkgs.jekyll
+            pkgs.rubyPackages.jekyll-redirect-from
+            pkgs.rubyPackages.github-pages
+          ];
+        };
+
+        packages.default = pkgs.stdenv.mkDerivation {
+          name = "snugg.ie";
+          src = ./.;
+          buildInputs = [
+            pkgs.ruby
+            pkgs.jekyll
+            pkgs.rubyPackages.jekyll-redirect-from
+            pkgs.rubyPackages.github-pages
+          ];
+          buildPhase = ''
+            jekyll build
+          '';
+          installPhase = ''cp -r _site $out'';
+        };
+      });
+}