feat: add a home-manager example configuration

This adds a home-manager example configuration to ensure the
home-manager standalone module works properly.

example-hm/home.nix

@@ -0,0 +1,70 @@
+{
+  lib,
+  pkgs,
+  config,
+  ...
+}:
+{
+  home = {
+    homeDirectory = "/home/jdoe";
+    stateVersion = "25.05";
+    username = "jdoe";
+  };
+
+  jhome = {
+    enable = true;
+    dev = {
+      enable = true;
+      neovimAsManPager = true;
+      rust.enable = true;
+    };
+    gui.enable = false;
+    hostName = "example";
+    user = {
+      enable = true;
+      defaultIdentity = {
+        email = "jdoe@example.org";
+        name = "John Doe";
+      };
+    };
+  };
+
+  programs = {
+    # Switch to fish if bash is started interactively
+    bash.initExtra = ''
+      if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
+      then
+        shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
+        exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
+      fi
+    '';
+
+    # Enable zellij (tmux like terminal session manager)
+    zellij.enable = lib.mkForce true;
+  };
+
+  nix = {
+    package = pkgs.lix;
+    gc = {
+      automatic = true;
+      frequency = "weekly";
+      options = "--delete-older-than 30d";
+      # run between 0 and 45min after boot if run was missed
+      randomizedDelaySec = "45min";
+    };
+    settings = {
+      # Add my personal binary cache to the mix (only for personal computers)
+      extra-substituters = [ "https://cache.salame.cl" ];
+      extra-trusted-public-keys = [ "cache.salame.cl:D+pBaoutwxja7qKGpju+CmM1LRbVmf2gqEQ/9c7qHrw=" ];
+      auto-optimise-store = true;
+    };
+  };
+
+  stylix = {
+    image = config.jhome.gui.sway.background;
+    base16Scheme = "${pkgs.base16-schemes}/share/themes/gruvbox-dark-hard.yaml";
+  };
+
+  # Let Home Manager install and manage itself.
+  programs.home-manager.enable = true;
+}