Fix og-gen: Chrome headless truncates 630px card footer; capture at 900 and crop with sharp, pin footer via absolute pos

scripts/og-gen/template.html

@@ -63,7 +63,8 @@
   .terminal .fix { color: #3fb950; }
 
   .footer {
-    margin-top: auto; padding: 0 48px 34px;
+    position: absolute; left: 0; right: 0; bottom: 0;
+    padding: 0 48px 34px;
     display: flex; align-items: center; justify-content: space-between;
   }
   .footer .tags { color: #6b7c99; font-size: 17px; }