Split up base and add xonsh

Add Xonsh configurations from dotfiles
Split up the base configuration into more manageable sizes

profiles/base/nix.nix

@@ -0,0 +1,19 @@
+{ pkgs, ... }:
+
+{
+	# Enable flakes
+	nix = {
+		package = pkgs.nixFlakes;
+
+		# Keep freespace available, at a minimum, and enable Flakes
+		extraOptions = ''
+experimental-features = nix-command flakes
+min-free = ${toString (1024 * 1024 * 1024) }
+max-free = ${toString (5 * 1024 * 1024 * 1024) }
+'';
+
+		# Use hardlinking instead of copying when possible
+		autoOptimiseStore = true;
+	};
+	nixpkgs.config.allowUnfree = true;
+}