refactor: Make more modular and do some refactoring

hosts/common.nix

@@ -0,0 +1,47 @@
+# ============================================================================
+# Common Modules
+# ============================================================================
+# This module contains all the common configuration shared by all host types.
+# It includes:
+# - Boot and user configuration
+# - Software configurations
+# - User management (users.nix)
+# - Home Manager integration
+# - Secret management (agenix)
+# - Disk partitioning (disko)
+# - System-wide Nix settings (experimental features, garbage collection)
+
+{ inputs }:
+{
+  config,
+  lib,
+  ...
+}:
+{
+  imports = [
+    ./boot.nix
+    ./user-config.nix
+    ../sw
+    ../users.nix
+    inputs.home-manager.nixosModules.home-manager
+    inputs.agenix.nixosModules.default
+    inputs.disko.nixosModules.disko
+  ];
+
+  system.stateVersion = "25.11";
+
+  nix.settings.experimental-features = [
+    "nix-command"
+    "flakes"
+  ];
+
+  # Automatic Garbage Collection
+  nix.gc = lib.mkIf config.ugaif.system.gc.enable {
+    automatic = true;
+    dates = config.ugaif.system.gc.frequency;
+    options = "--delete-older-than ${toString config.ugaif.system.gc.retentionDays}d";
+  };
+
+  # Optimize storage
+  nix.optimise.automatic = config.ugaif.system.gc.optimise;
+}