Add free-type spell checker for students

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

package.json

@@ -11,9 +11,11 @@
   "author": "NateEmmert",
   "license": "ISC",
   "dependencies": {
+    "dictionary-en": "^4.0.0",
     "express": "^5.1.0",
     "mammoth": "^1.12.0",
-    "multer": "^2.2.0"
+    "multer": "^2.2.0",
+    "nspell": "^2.1.5"
   },
   "engines": {
     "node": ">=24"