Initial commit: DNS Test - DNS health checking tool

Go backend (miekg/dns) + Nuxt 3 frontend (Tailwind CSS v4).

8 check categories, 52 checks total:
- Overview: @ record, WWW, MX with ASN/provider lookup
- Domain Registration: expiry, registrar (RDAP + whois fallback)
- Parent Delegation: NS records, glue, consistency
- Nameservers: 17 checks (reachability, auth, recursion, TCP/UDP, AXFR, etc.)
- SOA: serial consistency, timing values
- Mail (MX): 11 checks (CNAME, PTR, public IPs, consistency)
- Mail Auth: SPF, DKIM, DMARC
- WWW: A record, CNAME

Features:
- SSE streaming (results appear as each category completes)
- SQLite history (modernc.org/sqlite)
- Rate limiting, CORS, request logging
- Dark mode, responsive design

frontend/app/app.vue

@@ -0,0 +1,54 @@
+<template>
+  <div class="min-h-screen bg-gray-50 text-gray-900 dark:bg-gray-950 dark:text-gray-100">
+    <header class="border-b border-gray-200 bg-white dark:border-gray-800 dark:bg-gray-900">
+      <div class="mx-auto flex max-w-5xl items-center justify-between px-4 py-4 sm:px-6">
+        <NuxtLink to="/" class="flex items-center gap-2 text-xl font-bold tracking-tight text-indigo-600 dark:text-indigo-400">
+          <svg xmlns="http://www.w3.org/2000/svg" class="h-6 w-6" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+            <path stroke-linecap="round" stroke-linejoin="round" d="M21 12a9 9 0 01-9 9m9-9a9 9 0 00-9-9m9 9H3m9 9a9 9 0 01-9-9m9 9c1.657 0 3-4.03 3-9s-1.343-9-3-9m0 18c-1.657 0-3-4.03-3-9s1.343-9 3-9m-9 9a9 9 0 019-9" />
+          </svg>
+          DNS Test
+        </NuxtLink>
+        <button
+          @click="toggleTheme"
+          class="rounded-lg p-2 text-gray-500 hover:bg-gray-100 dark:text-gray-400 dark:hover:bg-gray-800"
+          aria-label="Toggle theme"
+        >
+          <svg v-if="isDark" xmlns="http://www.w3.org/2000/svg" class="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+            <path stroke-linecap="round" stroke-linejoin="round" d="M12 3v1m0 16v1m9-9h-1M4 12H3m15.364 6.364l-.707-.707M6.343 6.343l-.707-.707m12.728 0l-.707.707M6.343 17.657l-.707.707M16 12a4 4 0 11-8 0 4 4 0 018 0z" />
+          </svg>
+          <svg v-else xmlns="http://www.w3.org/2000/svg" class="h-5 w-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" stroke-width="2">
+            <path stroke-linecap="round" stroke-linejoin="round" d="M20.354 15.354A9 9 0 018.646 3.646 9.003 9.003 0 0012 21a9.003 9.003 0 008.354-5.646z" />
+          </svg>
+        </button>
+      </div>
+    </header>
+    <main>
+      <NuxtPage />
+    </main>
+    <footer class="mt-16 border-t border-gray-200 bg-white py-8 dark:border-gray-800 dark:bg-gray-900">
+      <div class="mx-auto max-w-5xl px-4 text-center text-sm text-gray-500 dark:text-gray-400 sm:px-6">
+        DNS Test &mdash; Check your domain's DNS health
+      </div>
+    </footer>
+  </div>
+</template>
+
+<script setup lang="ts">
+const isDark = ref(false)
+
+function toggleTheme() {
+  isDark.value = !isDark.value
+  if (isDark.value) {
+    document.documentElement.classList.add('dark')
+  } else {
+    document.documentElement.classList.remove('dark')
+  }
+}
+
+onMounted(() => {
+  if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+    isDark.value = true
+    document.documentElement.classList.add('dark')
+  }
+})
+</script>