- Enhance 404 page design and add link to home

- Update routes to include "Login" page
- Add dynamic website title updates based on current route
- Add "Login" button to layout linking to Login page

GUI/src/routes/404NotFound.vue

@@ -1,7 +1,17 @@
 <script setup lang="ts"></script>
 
 <template>
-  <h1>404</h1>
+  <v-container fluid class="fill-height d-flex flex-column justify-center align-center">
+    <h1 class="error-title text-h1 font-weight-bold">404</h1>
+    <p class="error-message text-h5">Page not found</p>
+
+    <router-link
+      to="/"
+      class="text-blue text-decoration-none font-weight-medium mt-5"
+    >
+      Zurück zur Startseite
+    </router-link>
+  </v-container>
 </template>
 
 <style scoped>
@@ -18,4 +28,7 @@
   opacity: 0.85;
   color: #fff;
 }
+a:hover {
+  text-decoration: underline !important;
+}
 </style>