Add engine field verification (#581)

I used `knip` as a good project to verify the latest addition of workspace support in my `installed-check` module, and I thought I could just as well send a PR in case you are interested in running it yourself

package.json

@@ -23,9 +23,12 @@
     "watch": "npm run watch --workspace packages/knip",
     "docs": "npm run dev --workspace packages/docs",
     "format": "npm run format --workspaces --if-present",
-    "test": "npm run qa --workspaces --if-present"
+    "test": "npm run qa --workspaces --if-present && installed-check --no-include-workspace-root --ignore-dev"
   },
   "peerDependencies": {
     "knip": "file:packages/knip"
+  },
+  "devDependencies": {
+    "installed-check": "^9.1.0"
   }
 }

packages/docs/package.json

@@ -10,6 +10,9 @@
     "url": "github:webpro/knip",
     "directory": "packages/docs"
   },
+  "engines": {
+    "node": "^18.17.0 || ^20.3.0 || >=21.0.0"
+  },
   "scripts": {
     "prebuild": "tsx scripts/generate-plugin-docs.ts",
     "build": "astro check && astro build",

packages/eslint-config/package.json

@@ -5,6 +5,9 @@
   "type": "module",
   "main": "./index.js",
   "types": "./index.d.ts",
+  "engines": {
+    "node": "^18.18.0 || >=20.0.0"
+  },
   "dependencies": {
     "@eslint/js": "^8.57.0",
     "@typescript-eslint/eslint-plugin": "^7.5.0",