feat(nix): add nix flakes

Signed-off-by: Lucas Sta Maria <lucas@priime.dev>

nix/hosts/common/sys.nix

@@ -0,0 +1,75 @@
+{ inputs, config, lib, pkgs, ... }: {
+  nixpkgs.config.allowUnfree = true;
+
+  nix = {
+    extraOptions = ''
+      extra-experimental-features = nix-command flakes
+      build-users-group = nixbld
+    '';
+    settings = {
+      trusted-users = [ "root" "priime" ];
+      substituters =
+        [ "https://cache.nixos.org/" "https://nix-community.cachix.org" ];
+      trusted-public-keys = [
+        "nix-community.cachix.org-1:mB9FSh9qf2dCimDSUo8Zy7bkq5CX+/rkCWyvRCYg3Fs="
+      ];
+      sandbox = true;
+    };
+    nixPath = [ "nixpkgs=${inputs.nixpkgs}" ];
+  };
+
+  environment.systemPackages = with pkgs;
+    let
+      packages = [
+        nixos-rebuild
+        coreutils
+        git
+        gnupg
+        bottom
+        htop
+        bat
+        jq
+        unzip
+        wget
+        curl
+        libtool
+        fish
+        gcc
+        gnumake
+        cmake
+        tldr
+        emacs
+        man-pages
+        gdb
+        zsh
+        alsa-utils
+        killall
+        feh
+        xcolor
+        xclip
+        xdotool
+        ripgrep
+
+        nix-index
+
+        cargo
+        rustup
+        rustfmt
+        clippy
+        rust-analyzer
+
+        python3
+
+        nodejs
+        yarn
+
+        racket
+
+        jdk8
+        jdk21
+        jdk22
+
+        nodejs_20
+      ];
+    in packages;
+}