Bump flatted 3.4.1 → 3.4.2 to fix prototype pollution

  Fixes GHSA-rf6f-7fwh-wjgh (CWE-1321). Dev-only dependency via
  eslint → file-entry-cache → flat-cache → flatted.

frontend/package-lock.json

@@ -4777,9 +4777,9 @@
       }
     },
     "node_modules/flatted": {
-      "version": "3.4.1",
-      "resolved": "https://registry.npmjs.org/flatted/-/flatted-3.4.1.tgz",
-      "integrity": "sha512-IxfVbRFVlV8V/yRaGzk0UVIcsKKHMSfYw66T/u4nTwlWteQePsxe//LjudR1AMX4tZW3WFCh3Zqa/sjlqpbURQ==",
+      "version": "3.4.2",
+      "resolved": "https://registry.npmjs.org/flatted/-/flatted-3.4.2.tgz",
+      "integrity": "sha512-PjDse7RzhcPkIJwy5t7KPWQSZ9cAbzQXcafsetQoD7sOJRQlGikNbx7yZp2OotDnJyrDcbyRq3Ttb18iYOqkxA==",
       "dev": true
     },
     "node_modules/foreground-child": {