feat(web-design): add web design service page and navigation

This commit introduces the new 'Web Design' service page.

- Creates the  route to showcase pricing plans for Landing Pages and Official Websites.
- Uses a tabbed layout to organize the different service tiers.
- Adds a '网展开发' link to the main navigation bar in the default layout for easy access.

app/layouts/default.vue

@@ -5,6 +5,8 @@
         <div class="text-2xl font-bold">Tootaio Studio</div>
       </template>
 
+      <UNavigationMenu :items="items" />
+
       <template #right>
         <UColorModeButton />
       </template>
@@ -39,6 +41,22 @@
 </template>
 
 <script setup lang="ts">
+import type { NavigationMenuItem } from "@nuxt/ui";
+
+const route = useRoute();
+
+const items = computed<NavigationMenuItem[]>(() => [
+  {
+    label: "宴会大屏展示",
+    to: "/",
+  },
+  {
+    label: "网展开发",
+    to: "/web-design",
+    active: route.path.startsWith("/web-design"),
+  },
+]);
+
 const socialLink = [
   {
     name: "Blog Posts",