fix case issues on userName

client/src/pages/RegisterForm.vue

@@ -10,7 +10,7 @@ import * as authApi from "../api/AuthApi";
 const router = useRouter();
 
 const user = reactive<RegisterDto>({ // the template ensures type consistency
-    username: "",
+    userName: "",
     email: "",
     password: "",
 });
@@ -40,7 +40,7 @@ async function register(): Promise<void> {
         <h2>Register</h2>
 
         <form @submit.prevent="register">
-            <input v-model="user.username" placeholder="username" />
+            <input v-model="user.userName" placeholder="username" />
             <input v-model="user.email" placeholder="email" />
             <input v-model="user.password" placeholder="password" />