feat: support all HTML elements allowed by Glitch (#1233)

Closes https://github.com/elk-zone/elk/issues/1230

tests/__snapshots__/content-rich.test.ts.snap

@@ -92,7 +92,7 @@ exports[`content-rich > handles formatting from servers 1`] = `
 <p></p>
 <ul>
   <li>This is an indented bulleted list (not just asterisks).</li>
-  <li></li>
+  <li><strong>This line is bold.</strong></li>
   <li><em>This line is italic.</em></li>
 </ul>
 <ol>