fix: добавлен build скрипт в корневой package.json

Делегирует npm run build в frontend workspace для CI/CD.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -1,5 +1,8 @@
 {
   "name": "test-x6",
   "private": true,
-  "workspaces": ["frontend"]
+  "workspaces": ["frontend"],
+  "scripts": {
+    "build": "npm run -w frontend build"
+  }
 }