build: use npm as the only package manager

.gitignore

@@ -4,7 +4,6 @@ logs
 npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
-pnpm-debug.log*
 lerna-debug.log*
 
 node_modules

.prettierignore

@@ -1,2 +1,2 @@
 dist
-pnpm-lock.yaml
+package-lock.json

README.md

@@ -59,25 +59,25 @@ Planned:
 
 > **Not relevant yet.** The first delivery is a specification, so you do not need to run anything to review it. These commands only start the starter project.
 
-You need Node 24 (see `.nvmrc`) and pnpm. If you have npm but not pnpm, install it with `npm install -g pnpm`.
+You need Node 24 (see `.nvmrc`). The project uses npm; do not use pnpm or yarn, so that everyone gets the versions in `package-lock.json`.
 
 ```bash
 nvm use
-pnpm install
-pnpm dev
+npm ci
+npm run dev
 ```
 
-`pnpm dev` starts the starter project at http://localhost:5173.
+`npm run dev` starts the starter project at http://localhost:5173.
 
 Other commands:
 
-| Command        | What it does                                    |
-| -------------- | ----------------------------------------------- |
-| `pnpm build`   | Type-checks and builds the project into `dist/` |
-| `pnpm preview` | Serves the built project locally                |
-| `pnpm lint`    | Runs ESLint                                     |
-| `pnpm format`  | Formats all files with Prettier                 |
-| `pnpm test`    | Runs the tests with Vitest                      |
+| Command           | What it does                                    |
+| ----------------- | ----------------------------------------------- |
+| `npm run build`   | Type-checks and builds the project into `dist/` |
+| `npm run preview` | Serves the built project locally                |
+| `npm run lint`    | Runs ESLint                                     |
+| `npm run format`  | Formats all files with Prettier                 |
+| `npm run test`    | Runs the tests with Vitest                      |
 
 ## Working in this repository
 

package.json

@@ -35,5 +35,8 @@
     "typescript-eslint": "^8.69.0",
     "vite": "^8.3.0",
     "vitest": "^5.0.2"
+  },
+  "engines": {
+    "node": ">=24"
   }
 }