Refactor NixOS configuration: Move GUI apps to desktop modules and create headless config

- Move GUI applications from users/jsutter.nix to appropriate desktop modules:
  * office.nix: slack, signal-desktop
  * gaming.nix: discord, stremio
  * plasma.nix: arc-theme, pinentry, tigervnc
  * dev.nix: putty
  * media.nix (new): vlc, deluge

- Create systems/common-headless.nix for server configurations:
  * Remove GUI dependencies (Flatpak, XDG portals, fonts, graphics drivers)
  * Include only essential CLI tools and server packages
  * Disable X server completely

- Simplify skip01 configuration:
  * Remove Intel graphics drivers and OpenGL support
  * Use headless common configuration
  * Keep unified users/jsutter.nix (no split files)

- Update flake.nix to include new media.nix module in desktop systems

Result: Clean separation between desktop and headless configurations
with improved modularity and maintainability.

systems/common-headless.nix

@@ -0,0 +1,153 @@
+{ config, pkgs, ... }:
+
+{
+  fileSystems."/" =
+    { device = "/dev/disk/by-partlabel/primary";
+      fsType = "btrfs";
+    };
+  fileSystems."/boot" =
+    { device = "/dev/disk/by-partlabel/ESP";
+      fsType = "vfat";
+    };
+
+  # hardware
+  hardware.enableRedistributableFirmware = true;
+  services.fwupd.enable = true;
+
+  # Network
+  networking = {
+    extraHosts = "";
+    networkmanager = {
+      enable = true;
+      plugins = with pkgs; [
+        networkmanager-openvpn
+        networkmanager-openconnect
+      ];
+    };
+    useDHCP = false; # Depreciated
+  };
+
+  # Bootloader
+  boot.loader.systemd-boot.enable = true;
+  boot.loader.efi.canTouchEfiVariables = true;
+
+  # Kernel
+  boot.kernelPackages = pkgs.linuxPackages_latest;
+
+  # Nix
+  nix = {
+    # Automate garbage collection
+    gc = {
+      automatic = true;
+      dates = "weekly";
+      options = "--delete-older-than 7d";
+    };
+    package = pkgs.nixVersions.stable;
+    settings = {
+      auto-optimise-store = true;
+      trusted-users = [ "root" "jsutter" ];
+      experimental-features = [ "nix-command" "flakes" ];
+    };
+  };
+
+  # Allow unfree packages
+  nixpkgs.config.allowUnfree = true;
+
+  # Set your time zone.
+  time.timeZone = "America/Los_Angeles";
+
+  # Select internationalisation properties.
+  i18n.defaultLocale = "en_US.UTF-8";
+
+  i18n.extraLocaleSettings = {
+    LC_ADDRESS = "en_US.UTF-8";
+    LC_IDENTIFICATION = "en_US.UTF-8";
+    LC_MEASUREMENT = "en_US.UTF-8";
+    LC_MONETARY = "en_US.UTF-8";
+    LC_NAME = "en_US.UTF-8";
+    LC_NUMERIC = "en_US.UTF-8";
+    LC_PAPER = "en_US.UTF-8";
+    LC_TELEPHONE = "en_US.UTF-8";
+    LC_TIME = "en_US.UTF-8";
+  };
+
+  # Enable CUPS to print documents (disabled for headless)
+  # services.printing.enable = true;
+
+  # Enable sound (disabled for headless)
+  # sound.enable = true;
+  # hardware.pulseaudio.enable = false;
+  # security.rtkit.enable = true;
+  # services.pipewire = {
+  #   enable = true;
+  #   alsa.enable = true;
+  #   alsa.support32Bit = true;
+  #   pulse.enable = true;
+  # };
+
+  # Define a user account. Don't forget to set a password with 'passwd'.
+  users.defaultUserShell = pkgs.zsh;
+  programs.zsh.enable = true;
+
+  # System state version
+  system.stateVersion = "24.05";
+
+  # List packages installed in system profile
+  environment.systemPackages = with pkgs; [
+    # Essential CLI tools for server management
+    vim
+    git
+    curl
+    wget
+    htop
+    iotop
+    nethogs
+    ncdu
+    tree
+    unzip
+    zip
+    jq
+    yq
+    tmux
+    screen
+    lsof
+    netcat
+    nmap
+    tcpdump
+    iftop
+    dnsutils
+    whois
+    rsync
+    pciutils
+    sysstat
+    powertop
+    gnupg
+    p7zip
+    openssl
+    gnumake
+    kopia
+    dig
+    python3
+    pv
+    stress
+    s-tui
+    clinfo
+    fwupd
+  ];
+
+  # No GUI services for headless
+  # services.flatpak.enable = false; # Explicitly disabled
+
+  # No fonts needed for headless
+  # fonts.packages = []; # No GUI fonts needed
+
+  # Disable X server completely for headless
+  services.xserver.enable = false;
+  
+  # Disable documentation to save space
+  documentation.nixos.enable = false; 
+
+  # Network optimizations
+  systemd.network.wait-online.enable = false;
+  boot.initrd.systemd.network.wait-online.enable = false;
+}