Fix bugs, convert thumbnail to png, add context menu

frontend/package.json

@@ -14,6 +14,7 @@
   },
   "dependencies": {
     "@tailwindcss/vite": "^4.3.0",
+    "date-fns": "^4.4.0",
     "fabric": "^7.4.0",
     "pdfjs-dist": "^6.0.227",
     "react": "^19.2.6",
@@ -27,7 +28,7 @@
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.2",
     "@types/fabric": "^5.3.11",
-    "@types/node": "^24.12.3",
+    "@types/node": "^24.13.2",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^6.0.1",