feat: Add og tag

Author: emscb

apps/pyconkr-2026/index.html

@@ -22,6 +22,14 @@
     <!-- https://developers.google.com/web/fundamentals/web-app-manifest/ -->
     <link rel="manifest" href="/site.webmanifest" />
 
+    <meta property="og:url" content="https://2026.pycon.kr" />
+    <meta property="og:title" content="PyCon Korea 2026" />
+    <meta property="og:image" content="slogan_logo.png" />
+    <meta property="og:description" content="PyCon Korea 2026" />
+    <meta property="og:site_name" content="PyCon Korea 2026" />
+    <meta property="og:locale" content="ko_KR" />
+    <meta property="og:type" content="website" />
+
     <meta
       name="viewport"
       content="width=device-width,