fix: correct Firefox extension ID format in manifest

Author: medyo

public/firefox.manifest.json

@@ -4,7 +4,7 @@
   },
   "browser_specific_settings": {
     "gecko": {
-      "id": "f8793186-e9da-4332-aa1e-dc3d9f7bb04c"
+      "id": "{f8793186-e9da-4332-aa1e-dc3d9f7bb04c}"
     }
   }
 }