Add devshell and envrc

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1 +1,2 @@
 result
+.direnv/

flake.nix

@@ -32,6 +32,15 @@
           config.allowUnfree = true;
         };
       };
+      allSystems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+      forAllSystems = f: nixpkgs.lib.genAttrs allSystems (system: f {
+        pkgs = import nixpkgs { inherit system; };
+      });
     in
     {
       nixosConfigurations = {
@@ -70,5 +79,12 @@
           ];
         };
       };
+      devShells = forAllSystems ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [
+            pre-commit
+          ];
+        };
+      });
     };
 }