[darwin] Add nix-darwin for work laptop

Adds nix-darwin
Simplifies emacs tree-sitter
Probably breaks vterm on linux :(

machines/johno-macbookpro/configuration.nix

@@ -0,0 +1,23 @@
+{ config, lib, pkgs, ... }:
+
+{
+  # Basic system configuration for macOS work laptop
+  system.stateVersion = 6;
+
+  # Set primary user for nix-darwin
+  system.primaryUser = "johno";
+
+  # System preferences (can be expanded later)
+  system.defaults = {
+    dock.autohide = true;
+    finder.AppleShowAllExtensions = true;
+    NSGlobalDomain.AppleShowAllExtensions = true;
+  };
+
+  # TODO: Find a way to not duplicate this
+  launchd.user.envVariables = {
+    # DOOM Emacs environment variables
+    DOOMDIR = "/Users/johno/.config/doom";
+    DOOMLOCALDIR = "/Users/johno/.local/doom";
+  };
+}