feat: set up direnv, formatter and format flake (#133)

* configure direnv

* chore(nix): configure formatter and run `nix fmt`

.envrc

@@ -0,0 +1,5 @@
+if ! has nix_direnv_version || ! nix_direnv_version 3.0.5; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.0.5/direnvrc" "sha256-RuwIS+QKFj/T9M2TFXScjBsLR6V3A17YVoEW/Q6AZ1w="
+fi
+
+use flake . --fallback --keep-going

.gitignore

@@ -5,3 +5,4 @@ result
 target/
 worker/
 .cargo/
+.direnv/

flake.nix

@@ -2,8 +2,10 @@
   description = "Template for Holochain app development";
 
   inputs = {
-    versions.url = "github:holochain/holochain/holochain-0.3.0-beta-dev.45?dir=versions/weekly";
-    versions.inputs.holochain.url = "github:holochain/holochain/holochain-0.3.0-beta-dev.45";
+    versions.url =
+      "github:holochain/holochain/holochain-0.3.0-beta-dev.45?dir=versions/weekly";
+    versions.inputs.holochain.url =
+      "github:holochain/holochain/holochain-0.3.0-beta-dev.45";
 
     holochain-flake.url = "github:holochain/holochain";
     holochain-flake.inputs.versions.follows = "versions";
@@ -13,26 +15,20 @@
   };
 
   outputs = inputs:
-    inputs.flake-parts.lib.mkFlake { inherit inputs; }
-      {
-        systems = builtins.attrNames inputs.holochain-flake.devShells;
+    inputs.flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = builtins.attrNames inputs.holochain-flake.devShells;
 
-        perSystem =
-          { inputs'
-          , config
-          , pkgs
-          , system
-          , ...
-          }: {
+      perSystem = { inputs', config, pkgs, system, ... }: {
+        formatter = pkgs.nixfmt-rfc-style;
 
-            devShells.default = pkgs.mkShell {
-              inputsFrom = [ inputs'.holochain-flake.devShells.holonix ];
-              packages = [
-                pkgs.nodejs-18_x
-                pkgs.binaryen
-                # more packages go here
-              ];
-            };
-          };
+        devShells.default = pkgs.mkShell {
+          inputsFrom = [ inputs'.holochain-flake.devShells.holonix ];
+          packages = [
+            pkgs.nodejs-18_x
+            pkgs.binaryen
+            # more packages go here
+          ];
+        };
       };
-}
+    };
+}