Add flakes and nixos stuff

src/slides.md

@@ -409,9 +409,104 @@ in "${pkgs.hello}"
 Flakes
 ===
 - Experimentales
+  - Pero no como piensas
 - Simplemente un **_wrapper_** para otras configuraciones de Nix
 - `flake.nix` `flake.lock`
 
+```nix +line_numbers {all|2-6|6-12}
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+  };
+
+outputs = { self, nixpkgs, ... }@inputs: {
+    nixosConfigurations.my-nixos = nixpkgs.lib.nixosSystem {
+      modules = [
+        ./configuration.nix
+      ];
+    };
+  };
+}
+```
+<!-- speaker_note: Comentar el parámetro especial self -->
+<!-- end_slide -->
+
+Configurar NixOS
+===
+`/etc/nixos/configuration.nix`
+```nix +line_numbers {all|10|12|all}
+{ config, pkgs, ... }:
+
+{
+  imports = [
+    ./hardware-configuration.nix
+  ];
+
+  # ......
+
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+  environment.systemPackages = with pkgs; [
+    git
+    vim
+    wget
+  ];
+  environment.variables.EDITOR = "vim";
+
+  # ......
+}
+```
+<!-- end_slide -->
+
+Configurar NixOS con Flakes
+===
+`/etc/nixos/flake.nix`
+```nix +line_numbers {all|11-12|all}
+{
+  description = "A simple NixOS flake";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
+  };
+
+  outputs = { self, nixpkgs, ... }@inputs: {
+    nixosConfigurations.my-nixos = nixpkgs.lib.nixosSystem {
+      modules = [
+        # Importamos lo que teníamos antes!
+        ./configuration.nix
+      ];
+    };
+  };
+}
+```
+
+<!-- speaker_note: Hablar del flake.lock que crea esto -->
+
+<!-- end_slide -->
+
+
+<!-- jump_to_middle -->
+Vamos a probar algunas cosas 🙃
+===
+
+<!-- end_slide -->
+Tips & tricks
+===
+
+- Si usas Git, Nix ignora todos los archivos no trackeados.
+- `sudo nix-collect-garbage --delete-old`
+- `sudo nix-store --optimise`
+
+```nix
+{
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    options = "--delete-older-than 7d";
+  };
+
+  nix.settings.auto-optimise-store = true;
+}
+```
 <!-- end_slide -->
 ¿Preguntas?
 ===