feat: placeholder images, Nostr inbox, order lookup, SEO, bigger logo

- 5 SVG placeholder product images (minimal dark style with watermark initials)
- Seed data updated to reference .svg placeholders
- Nostr DM inbox in admin (Messages tab) with shop npub display
- GET /api/admin/nostr-info endpoint for shop pubkey
- My Orders page: customers look up orders by NIP-07 Nostr identity
- GET /api/orders/by-pubkey/:pubkey endpoint with hex validation
- SeoMeta component for OG/Twitter meta tags
- SEO meta on HomeView and ProductView
- Base OG meta tags in index.html
- "My Orders" link in shop header nav
- Splash logo doubled in size on desktop (680px max)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/views/admin/MessagesView.vue

@@ -0,0 +1,62 @@
+<script setup lang="ts">
+import { ref, onMounted } from 'vue'
+import { api } from '@/api/client'
+import GlassCard from '@/components/ui/GlassCard.vue'
+
+const shopNpub = ref('')
+const isLoading = ref(true)
+
+onMounted(async () => {
+  try {
+    const res = await api.get('/api/admin/nostr-info')
+    if (res.ok) {
+      const data = await res.json() as { npub: string; pubkey: string }
+      shopNpub.value = data.npub
+    }
+  } finally {
+    isLoading.value = false
+  }
+})
+</script>
+
+<template>
+  <div>
+    <h1>Messages</h1>
+    <p class="subtitle">Customer communication via Nostr encrypted DMs</p>
+
+    <GlassCard v-if="shopNpub" class="info-card">
+      <h3>Shop Nostr Identity</h3>
+      <code class="npub">{{ shopNpub }}</code>
+      <p class="hint">Customers who provide their Nostr pubkey at checkout receive order updates as encrypted DMs from this identity.</p>
+      <div class="actions">
+        <a :href="`https://njump.me/${shopNpub}`" target="_blank" rel="noopener" class="btn btn-ghost">View on njump.me</a>
+        <a href="https://coracle.social" target="_blank" rel="noopener" class="btn btn-ghost">Open Coracle</a>
+      </div>
+    </GlassCard>
+
+    <GlassCard class="info-card">
+      <h3>Reading Customer DMs</h3>
+      <p>To read and reply to customer messages, import the shop's Nostr private key into any Nostr client:</p>
+      <ul>
+        <li><strong>Desktop:</strong> Coracle, Snort, or any NIP-04 compatible client</li>
+        <li><strong>iOS:</strong> Damus</li>
+        <li><strong>Android:</strong> Amethyst</li>
+      </ul>
+      <p class="warning">Never share the shop's private key. Only import it on trusted devices.</p>
+    </GlassCard>
+  </div>
+</template>
+
+<style scoped>
+h1 { font-size: 1.5rem; font-weight: 700; margin-bottom: 0.25rem; }
+.subtitle { color: var(--text-muted); font-size: 0.875rem; margin-bottom: 1.5rem; }
+.info-card { margin-bottom: 1.5rem; }
+.info-card h3 { font-size: 1rem; font-weight: 600; margin-bottom: 0.75rem; }
+.info-card p { font-size: 0.875rem; color: var(--text-secondary); margin-bottom: 0.75rem; line-height: 1.6; }
+.npub { display: block; font-size: 0.75rem; color: var(--accent); word-break: break-all; margin-bottom: 0.75rem; padding: 0.75rem; background: var(--glass-bg-darker); border-radius: var(--radius-sm); }
+.hint { font-size: 0.8125rem; color: var(--text-muted); }
+.actions { display: flex; gap: 0.75rem; margin-top: 1rem; }
+ul { font-size: 0.875rem; color: var(--text-secondary); padding-left: 1.25rem; margin-bottom: 0.75rem; }
+li { margin-bottom: 0.375rem; }
+.warning { color: var(--warning); font-size: 0.8125rem; font-weight: 500; }
+</style>