fix: Remove next() from Mongoose 9 async pre-save hook

Author: DevITJAX

backend/models/User.js

@@ -45,15 +45,14 @@ const UserSchema = new mongoose.Schema({
     }
 });
 
-// Encrypt password using bcrypt
-UserSchema.pre('save', async function (next) {
+// Encrypt password using bcrypt (Mongoose 9 async middleware - no next())
+UserSchema.pre('save', async function () {
     if (!this.isModified('password')) {
-        return next();
+        return;
     }
 
     const salt = await bcrypt.genSalt(10);
     this.password = await bcrypt.hash(this.password, salt);
-    next();
 });
 
 // Match user entered password to hashed password in database