Enable GNOME desktop by default on every NixOS host

Add GDM+GNOME, NetworkManager, PipeWire audio, and CUPS+Avahi
printing to modules/nixos/common.nix, applied unconditionally to
every NixOS host built from this flake, per add-gnome-desktop.
nix flake check remains unverified: Nix isn't installed on this
machine and no live NixOS host exists yet to boot-test against.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BBSd4VBfoKHjE1HR3P8kmn

1 files changed, 19 insertions, 0 deletions

diff --git a/modules/nixos/common.nix b/modules/nixos/common.nix
index df947c0..1b34e4e 100644
--- a/modules/nixos/common.nix
+++ b/modules/nixos/common.nix
@@ -38,4 +38,23 @@
     enable = true;
     allowedTCPPorts = [ 22 ];
   };
+
+  services.xserver.enable = true;
+  services.displayManager.gdm.enable = true;
+  services.desktopManager.gnome.enable = true;
+
+  networking.networkmanager.enable = true;
+
+  services.pipewire = {
+    enable = true;
+    pulse.enable = true;
+  };
+  security.rtkit.enable = true;
+
+  services.printing.enable = true;
+  services.avahi = {
+    enable = true;
+    nssmdns4 = true;
+    openFirewall = true;
+  };
 }