Harden deployment security

package.json

@@ -18,8 +18,9 @@
     "bcryptjs": "^2.4.3",
     "express": "^4.19.2",
     "express-session": "^1.18.1",
+    "helmet": "^8.3.0",
     "multer": "^2.2.0",
-    "nodemailer": "^6.9.14",
+    "nodemailer": "^9.0.3",
     "sanitize-html": "^2.13.0",
     "sharp": "^0.33.5",
     "slugify": "^1.6.6"