chore: added flake.nix

Author: aryanjassal

flake.lock

@@ -0,0 +1,46 @@
+{
+  inputs = {
+    nixpkgs-matrix = {
+      type = "indirect";
+      id = "nixpkgs-matrix";
+    };
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { nixpkgs-matrix, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs-matrix.legacyPackages.${system};
+        shell = { ci ? false }:
+          with pkgs;
+          pkgs.mkShell {
+            nativeBuildInputs = [ nodejs_20 shellcheck gitAndTools.gh ];
+            PKG_IGNORE_TAG = 1;
+            shellHook = ''
+              echo "Entering $(npm pkg get name)"
+              set -o allexport
+              . <(polykey secrets env js-virtualtar)
+              set +o allexport
+              set -v
+              ${lib.optionalString ci ''
+                set -o errexit
+                set -o nounset
+                set -o pipefail
+                shopt -s inherit_errexit
+              ''}
+              mkdir --parents "$(pwd)/tmp"
+
+              export PATH="$(pwd)/dist/bin:$(npm root)/.bin:$PATH"
+
+              npm install --ignore-scripts
+
+              set +v
+            '';
+          };
+      in {
+        devShells = {
+          default = shell { ci = false; };
+          ci = shell { ci = true; };
+        };
+      });
+}