chore(frontend): upgrade typescript to 6.0.x

Agent-Logs-Url: https://github.com/bg-playground/BGSTM/sessions/bc1794fc-6e38-4ae9-960a-67d8fef8b317

Co-authored-by: bg-playground <259109604+bg-playground@users.noreply.github.com>

Author: Copilot

frontend/package-lock.json

@@ -35,7 +35,7 @@
     "globals": "^17.3.0",
     "postcss": "^8.5.6",
     "tailwindcss": "^4.1.18",
-    "typescript": "~5.9.3",
+    "typescript": "~6.0.2",
     "typescript-eslint": "^8.48.0",
     "vite": "^8.0.3"
   }