chore: sync frontend lockfile with GPL-3.0 license field

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/package-lock.json

@@ -7,6 +7,7 @@
     "": {
       "name": "frontend",
       "version": "0.0.0",
+      "license": "GPL-3.0-or-later",
       "dependencies": {
         "@dnd-kit/core": "^6.3.1",
         "@dnd-kit/sortable": "^10.0.0",