feat: add comprehensive NixOS configuration documentation and structure

- Introduced `08-structure.md` detailing project structure, main files, and versioning.
- Created `README.md` for documentation overview and quick start guide.
- Added user-specific configurations for Alacritty, Vim, Micro, Git, Zsh, Tmux, and tools.
- Implemented system modules for desktop environment (KDE Plasma), audio (PipeWire), networking, and services (OpenSSH, GnuPG).
- Configured Nix settings with flakes support and garbage collection.
- Established user management for `ada` with necessary groups and shell settings.
- Enabled VirtualBox guest additions for improved VM experience.

nixos/modules/networking/default.nix

@@ -0,0 +1,16 @@
+{ ... }:
+
+{
+  # Имя хоста
+  networking.hostName = "nixos-vm";
+
+  # Включение NetworkManager
+  networking.networkmanager.enable = true;
+
+  # Конфигурация фаервола
+  networking.firewall = {
+    enable = true;
+    allowedTCPPorts = [ 22 ];  # SSH
+    # allowedUDPPorts = [ ... ];
+  };
+}