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.

machines/congenital-optimist/configuration.nix

@@ -0,0 +1,54 @@
+{
+  config,
+  pkgs,
+  inputs,
+  unstable,
+  ...
+}: {
+  imports = [
+    ./hardware-configuration.nix
+    
+    # System modules
+    ../../modules/system/fonts.nix
+    ../../modules/system/network.nix
+    ../../modules/system/applications.nix
+    
+    # Hardware modules
+    ../../modules/hardware/amd-workstation.nix
+    
+    # Desktop environments
+    ../../modules/desktop/common.nix
+    ../../modules/desktop/gnome.nix
+    ../../modules/desktop/cosmic.nix
+    ../../modules/desktop/sway.nix
+    
+    # Development tools
+    ../../modules/development/tools.nix
+    
+    # User configuration
+    ../../modules/users/geir.nix
+
+    # Virtualization configuration
+    ../../modules/virtualization/incus.nix
+    ../../modules/virtualization/libvirt.nix
+    ../../modules/virtualization/podman.nix
+  ];
+
+  # Boot configuration
+  boot.loader.grub = {
+    enable = true;
+    zfsSupport = true;
+    efiSupport = true;
+    efiInstallAsRemovable = true;
+    mirroredBoots = [
+      {
+        devices = ["nodev"];
+        path = "/boot";
+      }
+    ];
+  };
+
+  # Basic system configuration
+  nixpkgs.config.allowUnfree = true;
+  system.stateVersion = "23.11"; # DO NOT CHANGE - maintains data compatibility
+}