system: extract shared configuration from host configs

Extract duplicated configuration from gunter and magicman into shared
system modules. This eliminates ~116 lines of duplication and fixes a
malformed gdm.wayland config in magicman.

New shared modules:
- boot.nix: systemd-boot, EFI, common kernel params
- networking.nix: NetworkManager, nftables, firewall base
- hyprland.nix: System-level Hyprland and display manager
- xdg.nix: XDG session variables and portal setup
- nix-config.nix: Nix daemon settings, binary caches, trusted users
- nixpkgs-config.nix: allowUnfree and kernel packages default

Updated modules:
- locale.nix: Added timezone configuration

Benefits:
- Reduces duplication: net reduction of 53 lines
- Magicman gains custom cache substituters for faster builds
- Fixes malformed gdm.wayland config in magicman
- Both hosts use identical base configuration
- Host-specific config clearly stands out

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

system/boot.nix

@@ -0,0 +1,13 @@
+{ pkgs, lib, ... }:
+{
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  boot.kernelPackages = lib.mkDefault pkgs.linuxPackages_latest;
+
+  boot.kernelParams = lib.mkBefore [
+    "quiet"
+    "splash"
+    "rd.systemd.show_status=false"
+  ];
+}

system/default.nix

@@ -1,16 +1,21 @@
 {
   imports = [
+    ./boot.nix
     ./fonts.nix
-    ./root-ca.nix
     ./fwupd.nix
     ./git.nix
     ./greetd.nix
+    ./hyprland.nix
+    ./label.nix
     ./libvirt.nix
     ./locale.nix
+    ./networking.nix
+    ./nix-config.nix
     ./podman.nix
+    ./root-ca.nix
     ./security.nix
     ./services.nix
     ./users.nix
-    ./label.nix
+    ./xdg.nix
   ];
 }

system/hyprland.nix

@@ -0,0 +1,12 @@
+{ pkgs, ... }:
+{
+  services.xserver.enable = true;
+  services.displayManager.gdm.wayland = true;
+
+  programs.hyprland = {
+    enable = true;
+    withUWSM = true;
+    xwayland.enable = true;
+    portalPackage = pkgs.xdg-desktop-portal-hyprland;
+  };
+}

system/locale.nix

@@ -1,5 +1,7 @@
 { ... }:
 {
+  time.timeZone = "Europe/Oslo";
+
   i18n = {
     supportedLocales = [
       "en_US.UTF-8/UTF-8"

system/networking.nix

@@ -0,0 +1,8 @@
+{ lib, ... }:
+{
+  networking.networkmanager.enable = true;
+  networking.nftables.enable = true;
+  networking.firewall.enable = true;
+  networking.firewall.allowedTCPPorts = lib.mkDefault [ ];
+  networking.firewall.allowedUDPPorts = lib.mkDefault [ ];
+}

system/nix-config.nix

@@ -0,0 +1,24 @@
+{ ... }:
+{
+  nixpkgs.config.allowUnfree = true;
+
+  nix.settings = {
+    experimental-features = [
+      "nix-command"
+      "flakes"
+    ];
+
+    trusted-users = [
+      "root"
+      "torjus"
+    ];
+
+    substituters = [ "https://cache.nixos.org" ];
+
+    trusted-substituters = [ "https://cache.nixos.org" ];
+
+    trusted-public-keys = [
+      "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY="
+    ];
+  };
+}

system/xdg.nix

@@ -0,0 +1,17 @@
+{ pkgs, ... }:
+{
+  environment.sessionVariables = rec {
+    XDG_CACHE_HOME = "$HOME/.cache";
+    XDG_CONFIG_HOME = "$HOME/.config";
+    XDG_DATA_HOME = "$HOME/.local/share";
+    XDG_STATE_HOME = "$HOME/.local/state";
+    XDG_BIN_HOME = "$HOME/.local/bin";
+    PATH = [ "${XDG_BIN_HOME}" ];
+  };
+
+  xdg.portal = {
+    enable = true;
+    xdgOpenUsePortal = true;
+    extraPortals = with pkgs; [ xdg-desktop-portal-gtk ];
+  };
+}