feat: add Twitter meta tags for improved sharing and SEO

templates/edit.html

@@ -4,11 +4,18 @@
         <meta charset="utf-8" />
         <meta name="viewport" content="width=device-width, initial-scale=1" />
         <title>{{ run_id }} — Diagram → TikZ</title>
+
         <meta property="og:title" content="{{ run_id }} — Diagram → TikZ" />
         <meta property="og:description" content="View and edit the LaTeX/TikZ code for diagram {{ run_id }}." />
         <meta property="og:type" content="article" />
         <meta property="og:url" content="{{ base_path }}/d/{{ run_id }}" />
         <meta property="og:image" content="{{ base_path }}/d/{{ run_id }}/files/preview.png" />
+
+        <meta name="twitter:card" content="summary_large_image" />
+        <meta name="twitter:title" content="{{ run_id }} — Diagram → TikZ" />
+        <meta name="twitter:description" content="View and edit the LaTeX/TikZ code for diagram {{ run_id }}." />
+        <meta name="twitter:image" content="{{ base_path }}/d/{{ run_id }}/files/preview.png" />
+
         <link rel="preconnect" href="https://fonts.googleapis.com" />
         <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin />
         <link