feat(seo): add meta tags and page titles

Configure default head meta and title template in nuxt.config.ts
Add dynamic SEO meta tags and robots directives to all pages

nuxt.config.ts

@@ -6,6 +6,21 @@ export default defineNuxtConfig({
   devtools: { enabled: true },
   modules: ['@nuxt/ui'],
   css: ['~/assets/css/main.css'],
+  app: {
+    head: {
+      title: 'Dinner Ticket System',
+      titleTemplate: (titleChunk) => titleChunk && titleChunk !== 'Dinner Ticket System'
+        ? `${titleChunk} · Dinner Ticket System`
+        : 'Dinner Ticket System',
+      meta: [
+        { name: 'description', content: 'Dinner ticket booking, confirmation, receipt, and seat sharing system.' },
+        { property: 'og:site_name', content: 'Dinner Ticket System' },
+        { property: 'og:type', content: 'website' },
+        { name: 'twitter:card', content: 'summary' },
+        { name: 'theme-color', content: '#dc2626' }
+      ]
+    }
+  },
   runtimeConfig: {
     databaseUrl: '',
     redisUrl: '',