feat: initial NixOS home lab infrastructure setup

- Add modular flake-based NixOS configuration
- Implement GitOps foundation with CI/CD pipeline
- Create comprehensive documentation and branching strategy
- Add modular desktop environments (GNOME, Cosmic, Sway)
- Configure virtualization stack (Incus, Libvirt, Podman)
- Set up development tools and hardware-specific modules
- Establish user configuration with literate programming support

This commit represents the completion of Phase 1: Flakes Migration
with modular configuration, virtualization, and GitOps foundation.

modules/desktop/common.nix

@@ -0,0 +1,29 @@
+{ config, pkgs, ... }: {
+  # Common desktop configuration shared across all environments
+  
+  # XDG Portal configuration for Wayland/X11 compatibility
+  xdg.portal = {
+    enable = true;
+    wlr.enable = true;
+    extraPortals = [ pkgs.xdg-desktop-portal-gtk ];
+  };
+
+  # Display manager and session management
+  services.dbus.enable = true;
+  
+  # Common desktop packages
+  environment.systemPackages = with pkgs; [
+    # Basic desktop tools
+    firefox
+    alacritty
+    nautilus
+    
+    # Media and graphics
+    vlc
+    gimp
+    
+    # Utilities
+    gnome-tweaks
+    dconf-editor
+  ];
+}

modules/desktop/cosmic.nix

@@ -0,0 +1,11 @@
+{ config, pkgs, ... }: {
+  # Cosmic Desktop Environment (System76's new Rust-based DE)
+  services.desktopManager.cosmic.enable = true;
+  services.displayManager.cosmic-greeter.enable = true;
+  services.desktopManager.cosmic.xwayland.enable = true;
+  
+  # Cosmic-specific packages
+  environment.systemPackages = with pkgs; [
+    # Cosmic is still in development, most packages come with the DE
+  ];
+}

modules/desktop/gnome.nix

@@ -0,0 +1,22 @@
+{ config, pkgs, ... }: {
+  # GNOME Desktop Environment
+  services.xserver = {
+    enable = true;
+    desktopManager.gnome.enable = true;
+    xkb.layout = "no";
+  };
+
+  # GNOME-specific packages
+  environment.systemPackages = with pkgs; [
+    gnome-extension-manager
+    gnome-shell-extensions
+    dconf-editor
+    gnome-tweaks
+  ];
+  
+  # GNOME services
+  services.gnome = {
+    gnome-keyring.enable = true;
+    glib-networking.enable = true;
+  };
+}

modules/desktop/sway.nix

@@ -0,0 +1,28 @@
+{ config, pkgs, ... }: {
+  # Sway Window Manager (Wayland-based i3 replacement)
+  programs.sway = {
+    enable = true;
+    wrapperFeatures.gtk = true;
+  };
+
+  # Sway-specific packages
+  environment.systemPackages = with pkgs; [
+    # Core Sway tools
+    swaylock
+    swayidle
+    swaybg
+    
+    # Wayland utilities
+    waybar          # Status bar
+    fuzzel          # Application launcher
+    gammastep       # Blue light filter
+    mako            # Notification daemon
+    flameshot       # Screenshot tool
+    wl-clipboard    # Clipboard utilities
+    
+    # Additional Wayland tools
+    grim            # Screenshot utility
+    slurp           # Screen area selection
+    wf-recorder     # Screen recorder
+  ];
+}