loop/webui: add prettier
diff --git a/loop/webui/package.json b/loop/webui/package.json
index 44d3a78..22227dd 100644
--- a/loop/webui/package.json
+++ b/loop/webui/package.json
@@ -12,6 +12,7 @@
   "scripts": {
     "check": "tsc --noEmit",
     "demo": "web-dev-server -config ./web-dev-server.config.mjs --node-resolve --open /src/web-components/demo/",
+    "format": "prettier ./src --write",
     "build": "tsc",
     "watch": "tsc --watch",
     "test": "tsc && wtr --coverage",
@@ -40,6 +41,7 @@
     "@web/test-runner-puppeteer": "^0.18.0",
     "autoprefixer": "^10.4.21",
     "esbuild": "^0.25.1",
+    "prettier": "3.5.3",
     "typescript": "^5.8.2"
   },
   "keywords": []