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/virtualization/incus.nix

@@ -0,0 +1,19 @@
+{ config, pkgs, ... }:
+{
+  virtualisation.incus = {
+    enable = true;
+    ui.enable = true;
+    package = pkgs.incus;
+  };
+
+  environment.systemPackages = with pkgs; [
+    incus
+    lxc
+  ];
+  users.users.geir = {
+    extraGroups = [ 
+      "incus-admin"
+    ];
+  };
+  networking.firewall.allowedTCPPorts = [ 8443 ];
+}