chore: upgrade npm packages for security and stability

Backend upgrades:
- i18next: 25.3.1 → 25.3.2 (patch)
- bcrypt: 5.1.1 → 6.0.0 (maintains compatibility)
- nodemailer: 6.10.1 → 7.0.5 (no AWS SES impact)
- sharp: 0.32.6 → 0.34.3 (image processing)
- chokidar: 3.6.0 → 4.0.3 (file watching)

Frontend upgrades:
- date-fns: 2.30.0 → 4.1.0 (date utilities)
- lucide-react: 0.292.0 → 0.525.0 (icons)
- react-toastify: 9.1.3 → 11.0.5 (notifications)

All upgrades tested, 0 npm audit vulnerabilities maintained.
Deferred high-risk upgrades (archiver, React 19, Express 5).

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/package.json

@@ -25,7 +25,7 @@
     "@types/react-google-recaptcha": "^2.1.9",
     "axios": "^1.3.2",
     "clsx": "^2.0.0",
-    "date-fns": "^2.29.3",
+    "date-fns": "4.1.0",
     "dompurify": "^3.2.6",
     "i18next": "^25.3.1",
     "i18next-browser-languagedetector": "^8.2.0",
@@ -33,7 +33,7 @@
     "js-cookie": "^3.0.5",
     "lodash": "^4.17.21",
     "lowlight": "^2.9.0",
-    "lucide-react": "^0.292.0",
+    "lucide-react": "0.525.0",
     "react": "^18.3.1",
     "react-countdown": "^2.3.5",
     "react-dom": "^18.3.1",
@@ -42,7 +42,7 @@
     "react-image-gallery": "^1.2.11",
     "react-intersection-observer": "^9.4.3",
     "react-router-dom": "^6.8.0",
-    "react-toastify": "^9.1.1",
+    "react-toastify": "11.0.5",
     "tailwind-merge": "^3.3.1"
   },
   "devDependencies": {