spotlights-macbook-air: Migrate to Darwin subdirectory

There's also a `spotlights-macbook-air` under NixOS, and it would be preferable to eventually have it in-tree.

hosts/spotlights-macbook-air/configuration.nix

@@ -1,70 +0,0 @@
-{ lib, pkgs, system, ... }: {
-  environment = {
-    # We'll use Vim globally.
-    systemPackages = [
-      pkgs.vim
-    ];
-    variables.EDITOR = "${pkgs.vim}/bin/vim";
-  };
-
-  # Per https://github.com/LnL7/nix-darwin/issues/663,
-  # nix-darwin only supports a few specific named activation scripts.
-  # We'll leverage `extraActivation` to symlink our JDKs.
-  system.activationScripts.extraActivation.text = ''
-    ##############
-    # Latest JDK #
-    ##############
-    # Regardless of version, we'd like the latest JDK available.
-
-    # Remove the symlink if it doesn't already exist.
-    rm -f /Library/Java/JavaVirtualMachines/zulu-latest.jdk
-
-    # We should only have a single JDK present within our package,
-    # but let's limit `find` regardless.
-    JDK_LOCATION="$(find "${pkgs.jdk}" -name "*.jdk" | head -n1)"
-
-    # Symlink!
-    ln -sf "$JDK_LOCATION" "/Library/Java/JavaVirtualMachines/zulu-latest.jdk"
-
-    ##########
-    # JDK 17 #
-    ##########
-    # We'd also like JDK 17 available, for legacy purposes.
-    # (The author of this is as disappointed in this as the reader should be.)
-    rm -f /Library/Java/JavaVirtualMachines/zulu-17.jdk
-    ln -sf "${pkgs.jdk17}/zulu-17.jdk" "/Library/Java/JavaVirtualMachines/zulu-17.jdk"
-  '';
-
-  # Auto upgrade nix package and the daemon service.
-  services.nix-daemon.enable = true;
-  nix = {
-    # Keep the latest version of Nix.
-    package = pkgs.nix;
-    # Necessary for using flakes on this system.
-    settings.experimental-features = "nix-command flakes";
-  };
-
-  # Create /etc/zshrc that loads the nix-darwin environment.
-  programs.zsh.enable = true;
-
-  # Used for backwards compatibility, please read the changelog before changing.
-  # $ darwin-rebuild changelog
-  system.stateVersion = 4;
-
-  nixpkgs = {
-    hostPlatform = lib.mkDefault "aarch64-darwin";
-
-    # Regretfully, we use some non-free packages.
-    config.allowUnfreePredicate = pkg: builtins.elem (lib.getName pkg) [
-      # Visual Studio Code
-      "vscode"
-    ];
-  };
-
-  # Our singular user!
-  users.users.spot = {
-    description = "Spotlight Deveaux";
-    home = "/Users/spot";
-    shell = pkgs.zsh;
-  };
-}