docs(og): add 1920×1080 cover art set + wire og-01 as og:image

docs/index.html

@@ -10,9 +10,14 @@
 <meta property="og:description" content="On-device, dyslexia-aware ESL tutor for L1-Japanese kids. Orton-Gillingham phonics × yokai mentor × CoreML wav2vec2. Built in 5 days with Opus 4.7.">
 <meta property="og:type" content="website">
 <meta property="og:url" content="https://www.youtalk.jp/mora">
-<meta property="og:image" content="https://www.youtalk.jp/mora/img/yokai/sh.png">
+<meta property="og:image" content="https://www.youtalk.jp/mora/img/og/og-01-dyslexic.png">
+<meta property="og:image:width" content="1920">
+<meta property="og:image:height" content="1080">
+<meta property="og:image:alt" content="Mora — A different door into reading. Editorial wordmark with three yokai mentor cards and an on-device phoneme posterior visualization.">
 <meta name="twitter:card" content="summary_large_image">
 <meta name="twitter:site" content="@y_kondoh">
+<meta name="twitter:image" content="https://www.youtalk.jp/mora/img/og/og-01-dyslexic.png">
+<meta name="twitter:image:alt" content="Mora — A different door into reading. Editorial wordmark with three yokai mentor cards and an on-device phoneme posterior visualization.">
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
 <link href="https://fonts.googleapis.com/css2?family=Fraunces:opsz,wght,SOFT,WONK@9..144,300..900,0..100,0..1&family=Spectral:ital,wght@0,300;0,400;0,500;0,600;0,700;1,400;1,500&family=JetBrains+Mono:wght@400;500;700&display=swap" rel="stylesheet">