Fix share card image

Author: john-b-yang

templates/base.html

@@ -9,16 +9,19 @@
     <!-- Open Graph -->
     <meta property="og:type" content="website" />
     <meta property="og:title" content="CodeClash" />
+    <meta property="og:description" content="CodeClash: Benchmarking Goal-Oriented Software Engineering" />
     <meta property="og:url" content="https://codeclash.ai/" />
-    <meta property="og:image" content="https://codeclash.ai/static/images/misc/share.svg">
+    <meta property="og:image" content="https://codeclash.ai/static/images/misc/share.png">
     <meta property="og:image:width" content="1200" />
     <meta property="og:image:height" content="630" />
+    <meta property="og:image:alt" content="CodeClash - Benchmarking Goal-Oriented Software Engineering" />
 
     <!-- Twitter -->
     <meta name="twitter:card" content="summary_large_image" />
     <meta name="twitter:title" content="CodeClash" />
     <meta name="twitter:description" content="CodeClash: Benchmarking Goal-Oriented Software Engineering" />
-    <meta name="twitter:image" content="https://codeclash.ai/static/images/misc/share.svg" />
+    <meta name="twitter:image" content="https://codeclash.ai/static/images/misc/share.png" />
+    <meta name="twitter:image:alt" content="CodeClash - Benchmarking Goal-Oriented Software Engineering" />
 
     <!-- Google tag (gtag.js) -->
     <script async src="https://www.googletagmanager.com/gtag/js?id=G-N8Q0B783CD"></script>