build: add missing prepack script

Author: sgratzl

package.json

@@ -19,7 +19,8 @@
     "validate": "svelte-check",
     "lint": "eslint src --ext .ts,.js,.svelte && prettier --check \"**/*\"",
     "fix": "eslint src --ext .ts,.js,.svelte --fix && prettier --write \"**/*\"",
-    "prepare": "husky install"
+    "prepare": "husky install",
+    "prepack": "npm run build"
   },
   "devDependencies": {
     "@fortawesome/free-solid-svg-icons": "^5.15.3",