Add a devenv setup and switch to pnpm

.editorconfig

@@ -0,0 +1,13 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_style = space
+indent_size = 2
+insert_final_newline = true
+trim_trailing_whitespace = true
+max_line_length = 120
+
+[*.md]
+trim_trailing_whitespace = false

.envrc

@@ -0,0 +1,4 @@
+#!/bin/bash
+
+eval "$(devenv direnvrc)"
+use devenv

.github/workflows/ci.yml

@@ -13,25 +13,21 @@ jobs:
     steps:
       - uses: actions/checkout@v5
 
+      # The action reads the pnpm version from the packageManager field in package.json.
+      - name: Install pnpm
+        uses: pnpm/action-setup@v6
+
       - name: Use Node.js
         uses: actions/setup-node@v4
         with:
           node-version: "22"
-          cache: "npm"
-
-      - name: Cache node modules
-        uses: actions/cache@v4
-        with:
-          path: node_modules
-          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
-          restore-keys: |
-            ${{ runner.os }}-node-
+          cache: "pnpm"
 
       - name: Install dependencies
-        run: npm ci
+        run: pnpm install --frozen-lockfile
 
       - name: Run lint
-        run: npm run lint
+        run: pnpm run lint
 
       - name: Run build
-        run: npm run build
+        run: pnpm run build

.gitignore

@@ -12,3 +12,4 @@
 # devenv
 .devenv
 .devenv.flake.nix
+.pre-commit-config.yaml

.prettierignore

@@ -0,0 +1,2 @@
+pnpm-lock.yaml
+devenv.lock

README.md

@@ -5,9 +5,9 @@ Formats source code from stdin and writes the formatted code to stdout.
 ## Install
 
 ```sh
-npm install
-npm run build
-npm link
+pnpm install
+pnpm run build
+pnpm add --global "$PWD"
 ```
 
 ## Usage
@@ -46,3 +46,15 @@ open "Format JSON.shortcut"
 ```
 
 To see all the options, run `format-code shortcuts --help`.
+
+## Development
+
+The project uses [devenv](https://devenv.sh) to install Node.js and pnpm. To
+enter the dev shell, run:
+
+```sh
+devenv shell
+```
+
+If you use [direnv](https://direnv.net), run `direnv allow` one time. Then
+direnv loads the dev shell when you enter the folder.