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>

backend/package.json

@@ -21,8 +21,8 @@
     "adm-zip": "^0.5.16",
     "archiver": "^5.3.1",
     "axios": "^1.10.0",
-    "bcrypt": "^5.1.0",
-    "chokidar": "^3.5.3",
+    "bcrypt": "6.0.0",
+    "chokidar": "4.0.3",
     "cors": "^2.8.5",
     "dotenv": "^16.0.3",
     "express": "^4.18.2",
@@ -31,7 +31,7 @@
     "form-data": "^4.0.4",
     "handlebars": "^4.7.8",
     "helmet": "^7.0.0",
-    "i18next": "^25.3.1",
+    "i18next": "25.3.2",
     "i18next-browser-languagedetector": "^8.2.0",
     "i18next-http-backend": "^3.0.2",
     "joi": "^17.9.1",
@@ -41,10 +41,10 @@
     "mime-types": "^3.0.1",
     "multer": "^2.0.2",
     "node-cron": "^3.0.2",
-    "nodemailer": "^6.9.1",
+    "nodemailer": "7.0.5",
     "pg": "^8.16.3",
     "react-i18next": "^15.6.0",
-    "sharp": "^0.32.0",
+    "sharp": "0.34.3",
     "sqlite3": "^5.1.6",
     "uuid": "^11.1.0",
     "winston": "^3.8.2",