feat: add og-image for social media preview

- SVG source file with terminal design
- PNG export (2400x1260 high-res)
- ANVIL ASCII logo + tagline + URL

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

og-image.svg

@@ -0,0 +1,58 @@
+<svg width="1200" height="630" viewBox="0 0 1200 630" xmlns="http://www.w3.org/2000/svg">
+  <defs>
+    <linearGradient id="bgGrad" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#0d1117"/>
+      <stop offset="100%" style="stop-color:#0a0e14"/>
+    </linearGradient>
+    <pattern id="grid" width="40" height="40" patternUnits="userSpaceOnUse">
+      <path d="M 40 0 L 0 0 0 40" fill="none" stroke="#30363d" stroke-width="0.5" opacity="0.3"/>
+    </pattern>
+  </defs>
+
+  <!-- Background -->
+  <rect width="1200" height="630" fill="url(#bgGrad)"/>
+  <rect width="1200" height="630" fill="url(#grid)"/>
+
+  <!-- Terminal window frame -->
+  <rect x="60" y="60" width="1080" height="510" rx="12" fill="#0d1117" stroke="#30363d" stroke-width="2"/>
+
+  <!-- Title bar -->
+  <rect x="60" y="60" width="1080" height="40" rx="12" fill="#161b22"/>
+  <rect x="60" y="88" width="1080" height="12" fill="#161b22"/>
+
+  <!-- Window buttons -->
+  <circle cx="90" cy="80" r="7" fill="#ff5f56"/>
+  <circle cx="115" cy="80" r="7" fill="#ffbd2e"/>
+  <circle cx="140" cy="80" r="7" fill="#27c93f"/>
+
+  <!-- Terminal title -->
+  <text x="600" y="85" font-family="monospace" font-size="14" fill="#8b949e" text-anchor="middle">root@anvil-cloud:~</text>
+
+  <!-- ASCII Logo -->
+  <text x="100" y="180" font-family="monospace" font-size="28" fill="#3fb950" font-weight="bold">
+    <tspan x="100" dy="0"> █████╗ ███╗   ██╗██╗   ██╗██╗██╗</tspan>
+    <tspan x="100" dy="32">██╔══██╗████╗  ██║██║   ██║██║██║</tspan>
+    <tspan x="100" dy="32">███████║██╔██╗ ██║██║   ██║██║██║</tspan>
+    <tspan x="100" dy="32">██╔══██║██║╚██╗██║╚██╗ ██╔╝██║██║</tspan>
+    <tspan x="100" dy="32">██║  ██║██║ ╚████║ ╚████╔╝ ██║███████╗</tspan>
+    <tspan x="100" dy="32">╚═╝  ╚═╝╚═╝  ╚═══╝  ╚═══╝  ╚═╝╚══════╝</tspan>
+  </text>
+
+  <!-- HOSTING text -->
+  <text x="720" y="370" font-family="monospace" font-size="24" fill="#3fb950" opacity="0.8">HOSTING</text>
+
+  <!-- Tagline -->
+  <text x="100" y="450" font-family="sans-serif" font-size="32" fill="#c9d1d9">
+    엔지니어가 관리하는 Linux 서버
+  </text>
+
+  <!-- Subtitle -->
+  <text x="100" y="500" font-family="monospace" font-size="18" fill="#8b949e">
+    <tspan fill="#3fb950">$</tspan> 고객의 문제가 해결될 때까지, 우리는 멈추지 않습니다
+  </text>
+
+  <!-- URL -->
+  <text x="1100" y="540" font-family="monospace" font-size="16" fill="#58a6ff" text-anchor="end">
+    hosting.anvil.it.com
+  </text>
+</svg>