Added FHS compliant Nix devshell to test install to /usr/local/bin

flake.nix

@@ -0,0 +1,25 @@
+# NOTE: this devshell exists because I'm scared of my
+{
+  description = "FHS compliant devshell for Billie Hilton's g CLI";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+  }: let
+    system = "x86_64-linux";
+    pkgs = nixpkgs.legacyPackages.${system};
+    fhs = pkgs.buildFHSEnv {
+      name = "g-fhs-shell";
+      targetPkgs = pkgs:
+        with pkgs; [
+          shellcheck
+        ];
+    };
+  in {
+    devShells.${system}.default = fhs.env;
+  };
+}