[nix] Redo and restructure the entire config

Thanks @KaitlynEthylia :)

nix/system/default.nix

@@ -0,0 +1,20 @@
+{ importAll, ... }:
+
+{
+  imports = importAll [] ./.;
+
+  users.users.alyxia = {
+    name = "alyxia";
+    home = "/Users/alyxia";
+  };
+
+  # enable the gpg agent by default
+  programs.gnupg.agent.enable = true;
+
+  # if you use zsh (the default on new macOS installations),
+  # you'll need to enable this so nix-darwin creates a zshrc sourcing needed environment changes
+  programs.zsh.enable = true;
+
+  # tailscaled isn't automatically registered as a service that should run on installation.
+  services.tailscale.enable = true;
+}

nix/system/homebrew.nix

@@ -0,0 +1,90 @@
+{ ... }:
+
+{
+  homebrew = {
+    enable = true;
+    onActivation = {
+      autoUpdate = true;
+      cleanup = "zap";
+      upgrade = true;
+    };
+
+    taps = [
+      "drud/ddev"
+      "homebrew/cask-versions"
+      "int128/kubelogin"
+    ];
+
+    # Please do not the brew.
+    brews = [
+      "bear"
+      "composer"
+      "croc"
+      "ddev"
+      "deno"
+      "dotnet"
+      "ferium"
+      "gradle"
+      "kubelogin"
+      "mkcert"
+      "nss"
+      "pinentry-mac"
+      "pkg-config"
+      "poetry"
+      "rustup"
+      "sdl2"
+
+      # Fyra crap, but from Homebrew because someone doesn't know how to
+      # package libraries in nixpkgs
+      "appstream-glib"
+      "glib"
+      "gobject-introspection"
+      "gsettings-desktop-schemas"
+      "gtk4"
+      "gtksourceview5"
+      "libgee"
+    ];
+
+    casks = [
+      "1password"
+      "1password-cli"
+      "alt-tab"
+      "android-studio"
+      "audacity"
+      "background-music"
+      "browserstacklocal"
+      "db-browser-for-sqlite"
+      "discord"
+      "discord-ptb"
+      "docker"
+      "firefox"
+      "firefox-developer-edition"
+      "goland"
+      "google-chrome"
+      "intellij-idea"
+      "itch"
+      "iterm2"
+      "lens"
+      "minecraft"
+      "obs"
+      "orbstack"
+      "phpstorm"
+      "plexamp"
+      "raycast"
+      "readdle-spark"
+      "rider"
+      "rubymine"
+      "sequel-ace"
+      "shottr"
+      "slack"
+      "spotify"
+      "steam"
+      "texifier"
+      "thunderbird"
+      "transmit"
+      "typora"
+      "visual-studio-code"
+      "wine-stable"
+    ];
+  };
+}

nix/system/nix.nix

@@ -0,0 +1,20 @@
+{ ... }:
+
+{
+  services.nix-daemon.enable = true;
+
+  nix = {
+    settings.experimental-features = [ "nix-command" "flakes" ];
+    gc = {
+      automatic = true;
+      options = "--delete-older-than 8d";
+    };
+  };
+
+  nixpkgs = {
+    config = {
+      allowUnfree = true;
+      permittedInsecurePackages = [ "python-2.7.18.8" ];
+    };
+  };
+}