init(nix): adding the direnv for nix proposes

flake.nix

@@ -0,0 +1,36 @@
+{
+	description = "Shell for ft_irc 42 project";
+
+	inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+	inputs.flake-utils.url = "github:numtide/flake-utils";
+
+	outputs = { self, nixpkgs, flake-utils }:
+		flake-utils.lib.eachDefaultSystem (system:
+			let
+				pkgs = import nixpkgs {
+					inherit system;
+				};
+			in {
+				devShells.default = pkgs.mkShell {
+					name = "cpp-42";
+					buildInputs = with pkgs; [
+						clang
+						clang-tools
+						irssi
+					] ++ (
+						if pkgs.stdenv.isLinux then [
+							valgrind
+						] else []
+					);
+					
+					shellHook = ''
+						export NIX_SHOW_STATS=0
+						export NIX_HIDE_STATS=1
+						export CXX=clang++
+						export CXXFLAGS="-std=cpp98 -Wall -Werror -Wextra"
+						printf "\n\033[0;90mCPP env loaded for: \033[38;5;220m${system}\033[0m\n"
+					'';
+					};
+				}
+		);
+}